LONG-TERM DEBT - Exit Credit Facility (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Oct. 04, 2019	May 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Exit Credit Facility
Credit facility, maximum borrowing capacity	$ 50.0		$ 110.0
Period the projected production volumes must be hedged	18 months
Total debt to earnings ratio, dividends or distributions to shareholders, maximum	2.75
Unused availability percentage, dividends or distributions to shareholders, minimum	15
Revolving Credit Facility [Member]
Exit Credit Facility
Reduction in borrowing base			$ 150.3
Debt instrument ratio current consolidated assets to current consolidated liabilities	1.0
Debt instrument covenant percentage related to projected production volumes	70.00%
Maximum amount of cash that may be held per covenant, as a percent of borrowing base	5.00%
Maximum amount of cash that may be held if more than the specified percentage of borrowing base	$ 30.0
Revolving Credit Facility [Member] | Secured Debt [Member]
Exit Credit Facility
Credit facility, maximum borrowing capacity	$ 1,000.0
Credit facility expiration date	Feb. 26, 2021
Weighted average effective interest rate					5.10%
Reduction in borrowing base	$ 60.0			$ 2.0
Line of credit, borrowing base				$ 260.3
Standby Letters of Credit [Member]
Exit Credit Facility
Credit facility, maximum borrowing capacity	50.0
Letter of credit outstanding	$ 0.1
Minimum | Revolving Credit Facility [Member]
Exit Credit Facility
Debt instrument covenant percentage of total value of mortgaged properties evaluated in reserve report	95.00%
Maximum | Revolving Credit Facility [Member]
Exit Credit Facility
Total debt to earnings ratio required under credit facility	4.0
Borrowing Base Determination, Period One | Revolving Credit Facility [Member]
Exit Credit Facility
Borrowing base scheduled redetermination date	--04-01
Borrowing Base Determination, Period Two | Revolving Credit Facility [Member]
Exit Credit Facility
Borrowing base scheduled redetermination date	--10-01
Subsequent Event | Letter of Credit | Standby Letters of Credit [Member]
Exit Credit Facility
Credit facility, maximum borrowing capacity		$ 2.0
Subsequent Event | Revolving Credit Facility [Member]
Exit Credit Facility
Credit facility, maximum borrowing capacity		$ 10.0