Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 134,587	$ (58,576)	$ (964,981)	$ (377,042)
Effective income tax rate, percent			25.91%	22.53%
Federal Statutory income tax rate, percent			21.00%		35.00%
CARES Act NOL Carryback			$ 156,000