Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Gains (Losses) [Member]	Treasury Stock [Member]
Impact of change in accounting principle	$ (14,812)			$ (14,812)
Begining Balance at Dec. 31, 2017	3,774,261	$ 1,441	$ 2,011,397	1,964,497	$ (5)	$ (203,069)
Beginning Balance, shares at Dec. 31, 2017		144,085,292				6,857,510
Adjusted balance at Dec. 31, 2017	3,759,449	$ 1,441	2,011,397	1,949,685	(5)	$ (203,069)
Adjusted balance, shares at Dec. 31, 2017		144,085,292				6,857,510
Net (loss) income	19,321			19,321
Stock-based compensation, net of tax	864	$ 1	1,596			$ (733)
Stock-based compensation, net of tax, shares		164,271				49,082
Net loss on derivative financial instruments	(2)				(2)
Ending Balance at Mar. 31, 2018	3,779,632	$ 1,442	2,012,993	1,969,006	(7)	$ (203,802)
Ending Balance, shares at Mar. 31, 2018		144,249,563				6,906,592
Begining Balance at Dec. 31, 2018	3,584,653	$ 1,444	2,018,143	1,769,415	21	$ (204,370)
Beginning Balance, shares at Dec. 31, 2018		144,383,662				6,945,309
Net (loss) income	(73,328)			(73,328)
Stock-based compensation, net of tax	570	$ 2	1,412			$ (844)
Stock-based compensation, net of tax, shares		223,330				81,480
Net loss on investments	(18)				(18)
Net loss on derivative financial instruments	(1)				(1)
Ending Balance at Mar. 31, 2019	$ 3,511,876	$ 1,446	$ 2,019,555	$ 1,696,087	$ 2	$ (205,214)
Ending Balance, shares at Mar. 31, 2019		144,606,992				7,026,789