Condensed Statements of Shareholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings	AOCI Attributable to Parent [Member]
Effect of ASU Implementation	$ 1,928,504	$ 7	$ 371,225	$ (67,016)	$ 1,625,481	$ (1,193)
Beginning balance at Dec. 31, 2018	1,928,504	7	371,225	(67,016)	1,625,481	(1,193)
Effect of ASU Implementation	1,977,656	7	374,896	(72,239)	1,676,008	(1,016)
Share-based compensation	3,671		3,671
Repurchase of common stock	(5,223)			(5,223)
Proceeds from options exercised	0
Changes in comprehensive income	177					177
Net income (loss)	56,076
Ending balance at Mar. 31, 2019	1,977,656	7	374,896	(72,239)	1,676,008	(1,016)
Effect of ASU Implementation	1,977,656	7	374,896	(72,239)	1,676,008	(1,016)
Effect of ASU Implementation	2,261,332	7	379,380	(72,455)	1,955,187	(787)
Beginning balance at Dec. 31, 2019	2,261,332	7	379,380	(72,455)	1,955,187	(787)
Effect of ASU Implementation	2,261,332	7	383,186	(73,991)	1,925,750	(561)
Share-based compensation	3,790		3,790
Repurchase of common stock	(1,536)			(1,536)
Proceeds from options exercised	16		16
Changes in comprehensive income	226					226
Net income (loss)	(27,828)
Ending balance at Mar. 31, 2020	2,234,391	7	383,186	(73,991)	1,925,750	(561)
Effect of ASU Implementation	$ 2,234,391	$ 7	$ 383,186	$ (73,991)	$ 1,925,750	$ (561)