Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 20,820	$ 156,256
Effective income tax rate, percent	(2.37%)	19.73%
Federal Statutory income tax rate, percent	21.00%