Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Federal statutory income tax rate, percent	21.00%		35.00%
Tax benefit from change in enacted tax rate	$ 0	[1]	$ (81,307)	$ 0	[1]
Income tax expense (benefit)	(13,996)		$ (57,678)	$ (71,194)
Operating loss carryforwards	$ 576,900
Operating loss carryforwards expiration	expire from 2021 to 2037

[1] In 2017, the revaluation from the Tax Act.