NATURE OF OPERATIONS AND ACCOUNTING POLICIES ERA Savings Plan (Details) - USD ($) $ in Millions |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2013 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
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| Defined Contribution Pension and Other Postretirement Plans [Line Items] | ||||
| Percent of employer contribution | 3.00% | |||
| Employer matching contribution, percent | 50.00% | 100.00% | ||
| Employer matching contribution, percent of employees' gross pay | 6.00% | 3.00% | ||
| Employer contribution | $ 3.2 | $ 3.6 | $ 1.1 | |
| X | ||||||||||
- Definition [Line Items] for Defined Contribution Pension and Other Postretirement Plans [Table] No definition available.
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| X | ||||||||||
- Definition Defined Contribution Plan, Percent of Employees' Gross Pay No definition available.
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| X | ||||||||||
- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. No definition available.
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| X | ||||||||||
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. No definition available.
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| X | ||||||||||
- Definition Percentage employer matches of the employee's percentage contribution matched. No definition available.
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