RECONCILIATION OF EARNINGS PER SHARE - Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income (Loss)	$ 262,430	$ (18,486)	$ 29,481	$ 33,403	$ (54,470)	$ 53,314	$ 36,759	$ (203,116)	$ 306,828	$ (167,513)	$ (945,731)
Basic Shares Outstanding (in shares)									97,182,477	94,475,797	76,078,371
Basic Earnings Per Average Common Share (in dollars per share)	$ 2.70	$ (0.19)	$ 0.30	$ 0.34	$ (0.56)	$ 0.55	$ 0.38	$ (2.34)	$ 3.16	$ (1.77)	$ (12.43)
Effect of dilutive securities
Net Income (Loss), Diluted EPS	$ 262,430	$ (18,486)	$ 29,481	$ 33,403	$ (54,470)	$ 53,314	$ 36,759	$ (203,116)	$ 306,828	$ (167,513)	$ (945,731)
Diluted Shares Outstanding (in shares)									97,707,408	94,475,797	76,078,371
Diluted Earnings Per Average Common Share (in dollars per share)	$ 2.68	$ (0.19)	$ 0.30	$ 0.34	$ (0.56)	$ 0.55	$ 0.38	$ (2.34)	$ 3.14	$ (1.77)	$ (12.43)
Stock options
Effect of dilutive securities
Effect of dilutive securities (in shares)									26,000	0	0
Non-vested restricted stock
Effect of dilutive securities
Effect of dilutive securities (in shares)									300,000	0	0
Performance share awards
Effect of dilutive securities
Effect of dilutive securities (in shares)									199,000	0	0