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]
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	440,822	287,858	152,964	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	10,475	0	0	0	0	10,475	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
AMPS Impact on Stockholders Equity	(296,634)	(81,686)	0	0	0	8,012	0	(222,960)
Ending balance at Sep. 30, 2018	1,798,809	1,441,857	97,825	0	454	218,050	(527)	41,150
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Warrant Exercises	3	0	0	0	0	3	0	0
Beginning 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]
Total comprehensive income	29,812	(22,159)	51,971	0	0	0	0	0
Stock-based compensation	1,710	0	0	0	0	1,710	0	0
AMPS Impact on Stockholders Equity	(296,634)	(81,686)	0	0	0	8,012	0	(222,960)
Ending balance at Sep. 30, 2018	1,798,809	1,441,857	97,825	0	454	218,050	(527)	41,150
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	(30,392)	(105,514)	75,122	0	0	0	0	0
Stock-based compensation	9,699	0	0	0	0	9,699	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(2,610)	(2,736)	0	0	0	0	126	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 Sep. 30, 2019	1,628,664	1,313,052	26,407	0	456	229,128	(347)	59,968
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from Warrant Exercises	0
Beginning 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]
Total comprehensive income	73,435	66,116	7,319	0	0	0	0	0
Stock-based compensation	2,334	0	0	0	0	2,334	0	0
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(21)	(54)	0	0	0	0	33	0
Ending balance at Sep. 30, 2019	$ 1,628,664	$ 1,313,052	$ 26,407	$ 0	$ 456	$ 229,128	$ (347)	$ 59,968