Annual report pursuant to Section 13 and 15(d)

SHARE-BASED COMPENSATION AND OTHER EMPLOYEE BENEFIT PLANS - Allocation of Plan Assets (Details)

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SHARE-BASED COMPENSATION AND OTHER EMPLOYEE BENEFIT PLANS - Allocation of Plan Assets (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Mar. 31, 2020
Oct. 31, 2019
Mar. 31, 2019
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments $ 534,768 $ 477,137 $ 495,343 $ 478,350
Cash and cash equivalents        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 32,561 8,680    
Cash plus        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   10,788    
Equity investments- UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 1,518 992    
Equity investments- non UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 2,345 1,488    
Insurance Linked Securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 27,870 24,303    
Illiquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 25,938 28,271    
Liquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 102,373      
Property debt        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 34,078 31,247    
Alternatives        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 48,013 41,167    
Diversified growth (absolute return) funds        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 1,242 41,787    
Government debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 85,817 86,797    
Corporate debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 1,656 1,612    
Multi asset credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   40,918    
Insurance Policy        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 171,357 159,087    
Level 1        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 13,107 13,888    
Level 1 | Cash and cash equivalents        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 5,933 8,680    
Level 1 | Cash plus        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   0    
Level 1 | Equity investments- UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 1,518 992    
Level 1 | Equity investments- non UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 2,345 1,488    
Level 1 | Insurance Linked Securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 1 | Illiquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 1 | Liquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0      
Level 1 | Property debt        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 1 | Alternatives        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 1 | Diversified growth (absolute return) funds        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 1,242 868    
Level 1 | Government debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 414 248    
Level 1 | Corporate debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 1,656 1,612    
Level 1 | Multi asset credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   0    
Level 1 | Insurance Policy        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 2        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 290,287 244,644    
Level 2 | Cash and cash equivalents        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 26,628 0    
Level 2 | Cash plus        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   10,788    
Level 2 | Equity investments- UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 2 | Equity investments- non UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 2 | Insurance Linked Securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 27,870 24,303    
Level 2 | Illiquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 2 | Liquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 102,373      
Level 2 | Property debt        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 2 | Alternatives        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 48,013 41,167    
Level 2 | Diversified growth (absolute return) funds        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 40,919    
Level 2 | Government debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 85,403 86,549    
Level 2 | Corporate debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 2 | Multi asset credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   40,918    
Level 2 | Insurance Policy        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 231,374 218,605    
Level 3 | Cash and cash equivalents        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Cash plus        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   0    
Level 3 | Equity investments- UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Equity investments- non UK        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Insurance Linked Securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Illiquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 25,938 28,271    
Level 3 | Liquid credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0      
Level 3 | Property debt        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 34,078 31,247    
Level 3 | Alternatives        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Diversified growth (absolute return) funds        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Government debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Corporate debt securities        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments 0 0    
Level 3 | Multi asset credit        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments   0    
Level 3 | Insurance Policy        
Defined Benefit Plan, Plan Assets, Category [Line Items]        
Total investments $ 171,357 $ 159,087