Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Parent Company [Member]
Beginning balance at Dec. 31, 2017	$ 1,645,258	$ 1,233,845	$ (52,239)	$ 0	$ 453	$ 199,560	$ (471)	$ 264,110
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	411,010	310,017	100,993	0	0	0	0	0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification									$ 0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Accounting Standards Update 2016-01 [Member]		2,900	(2,900)
Stock-based compensation	8,765	0	0	0	0	8,765	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(1,116)	(1,060)	0	0	0	0	(56)	0
Stock Issued During Period, Value, New Issues	1	0	0	0	1	0	0	0
Ending balance at Jun. 30, 2018	2,063,921	1,545,702	45,854	0	454	208,328	(527)	264,110
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Warrant Exercises	3
Warrant Exercised During Period Value	3	0	0	0	0	3	0	0
Beginning balance at Mar. 31, 2018	2,109,165	1,541,464	99,476	0	454	204,172	(511)	264,110
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	(49,309)	4,313	(53,622)	0	0	0	0	0
Stock-based compensation	4,153	0	0	0	0	4,153	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(91)	(75)	0	0	0	0	(16)	0
Ending balance at Jun. 30, 2018	2,063,921	1,545,702	45,854	0	454	208,328	(527)	264,110
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Warrant Exercises	3	0	0	0	0	3	0	0
Beginning balance at Dec. 31, 2018	1,633,147	1,421,302	(48,715)	0	454	219,429	(473)	41,150
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	(103,827)	(171,630)	67,803	0	0	0	0	0
Stock-based compensation	7,365	0	0	0	0	7,365	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(2,589)	(2,682)	0	0	0	0	93	0
Stock Issued During Period, Value, New Issues	2	0	0	0	2	0	0	0
AMPS Impact on Stockholders Equity	18,818							18,818
Ending balance at Jun. 30, 2019	1,552,916	1,246,990	19,088	0	456	226,794	(380)	59,968
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Warrant Exercises	0
Beginning balance at Mar. 31, 2019	1,665,888	1,376,244	22,542	0	456	223,545	(813)	43,914
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income	(131,883)	(128,429)	(3,454)	0	0	0	0	0
Stock-based compensation	3,249	0	0	0	0	3,249	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(392)	(825)	0	0	0	0	433	0
AMPS Impact on Stockholders Equity	16,054							16,054
Ending balance at Jun. 30, 2019	$ 1,552,916	$ 1,246,990	$ 19,088	$ 0	$ 456	$ 226,794	$ (380)	$ 59,968