(LOSS) EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
(Loss) earnings per share - basic:
Net (loss) income	$ 44,824	$ (318,493)	$ 32,582	$ 41,190	$ 57,170	$ (31,083)	$ 60,207	$ 63,336	$ (199,897)	$ 149,630	$ 230,155
Income allocated to participating securities									(101)	(617)	(1,457)
(Loss) income available to common shareholders									$ (199,998)	$ 149,013	$ 228,698
Weighted-average shares outstanding									43,029	46,842	48,127
(Loss) earnings per share - basic	$ 1.06	$ (7.49)	$ 0.75	$ 0.93	$ 1.25	$ (0.67)	$ 1.26	$ 1.32	$ (4.65)	$ 3.18	$ 4.75
(Loss) earnings per share - diluted:
Net (loss) income	$ 44,824	$ (318,493)	$ 32,582	$ 41,190	$ 57,170	$ (31,083)	$ 60,207	$ 63,336	$ (199,897)	$ 149,630	$ 230,155
Income allocated to participating securities									(101)	(616)	(1,450)
Re-measurement of share-based awards classified as liabilities									0	(471)	59
(Loss) income available to common shareholders									$ (199,998)	$ 148,543	$ 228,764
Weighted-average shares outstanding									43,029	46,842	48,127
Dilutive impact of potential common shares									0	149	321
Weighted-average shares and potential common shares outstanding									43,029	46,991	48,448
(Loss) earnings per share - diluted	$ 1.06	$ (7.49)	$ 0.75	$ 0.93	$ 1.25	$ (0.67)	$ 1.25	$ 1.31	$ (4.65)	$ 3.16	$ 4.72
Antidilutive options excluded from calculation									1,347	1,209	262