Annual report pursuant to Section 13 and 15(d)

REVENUES (Details)

v3.10.0.1
REVENUES (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disaggregation of Revenue [Line Items]                      
Revenues $ 52,016 $ 54,610 $ 57,728 $ 57,322 $ 57,531 $ 61,385 $ 57,878 $ 54,527 $ 221,676 $ 231,321 $ 247,228
United States                      
Disaggregation of Revenue [Line Items]                      
Revenues                 157,267 152,187 171,121
Dry-Leasing                      
Disaggregation of Revenue [Line Items]                      
Revenues                 11,482 16,394 13,701
Dry-Leasing | United States                      
Disaggregation of Revenue [Line Items]                      
Revenues                 3,873 1,604 683
Dry-Leasing | Foreign                      
Disaggregation of Revenue [Line Items]                      
Revenues                 7,609 14,790 13,018
Operating Income                      
Disaggregation of Revenue [Line Items]                      
Revenues                 210,194 214,927 233,527
Operating Income | United States                      
Disaggregation of Revenue [Line Items]                      
Revenues                 153,394 150,583 170,438
Operating Income | Foreign                      
Disaggregation of Revenue [Line Items]                      
Revenues                 56,800 64,344 63,089
Operating Income | Oil and Gas                      
Disaggregation of Revenue [Line Items]                      
Revenues                 200,454 198,354 202,839
Operating Income | Oil and Gas | United States                      
Disaggregation of Revenue [Line Items]                      
Revenues                 143,654 134,010 139,750
Operating Income | Oil and Gas | Foreign                      
Disaggregation of Revenue [Line Items]                      
Revenues                 56,800 64,344 63,089
Operating Income | Emergency Response Services                      
Disaggregation of Revenue [Line Items]                      
Revenues                 9,740 11,502 24,973
Operating Income | Flightseeing                      
Disaggregation of Revenue [Line Items]                      
Revenues                 $ 0 $ 5,071 $ 5,715