Taxes on Income, Earnings Before Taxes (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 28, 2021
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income	$ 15,313,000	$ 19,274,000	$ 23,834,000	$ (519,772,000)	$ 4,319,000	$ 64,455,000	$ 62,709,000	$ 58,337,000	$ (461,351,000)	$ 189,820,000	$ 114,159,000
U.S. Federal [Abstract]
Current									(218,613,000)	(312,000)	0
Deferred									37,436,000	45,133,000	27,102,000
Total U.S. Federal									(181,177,000)	44,821,000	27,102,000
U.S. State [Abstract]
Current									3,421,000	76,000	(243,000)
Deferred									(12,273,000)	1,706,000	7,619,000
Total U.S. State									(8,852,000)	1,782,000	7,376,000
Foreign [Abstract]
Current									270,000	198,000	443,000
Deferred									0	0	160,000
Total Foreign									270,000	198,000	603,000
Consolidated [Abstract]
Current									(214,922,000)	(38,000)	200,000
Deferred									25,163,000	46,839,000	34,881,000
Total Provision (benefit) for taxes on income	(7,102,000)	$ (8,419,000)	$ (1,429,000)	$ (172,809,000)	$ 1,347,000	$ 16,305,000	$ 15,269,000	$ 13,880,000	$ (189,759,000)	$ 46,801,000	$ 35,081,000
Income Taxes [Abstract]
Effective income tax rate									21.00%	21.00%	21.00%	35.00%
Tax refund amount	(30,606,000)								$ (30,606,000)
Income tax receivable	$ 188,177,000								$ 188,177,000
Subsequent Events [Member]
Income Taxes [Abstract]
Tax refund amount													$ (119,493,000)
COVID-19 [Member]
Income Taxes [Abstract]
Operating losses tax year									2013 2014 2015 2016 2017
Tax benefit related to CARES Act									$ (59,659,000)
Decrease in deferred tax asset									$ (88,292,000)
COVID-19 [Member] | Maximum [Member]
Income Taxes [Abstract]
Number of years net operating losses carried									5 years
United States [Member]
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income									$ (461,569,000)	$ 190,839,000	$ 117,800,000
Foreign [Member]
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income									$ 218,000	$ (1,019,000)	$ (3,641,000)