Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Jan. 01, 2017
Income Taxes [Line Items]
U.S. federal statutory corporate pretax rate	35.00%
Deferred Tax Assets, Net	$ 0
Tax Adjustments, Settlements, and Unusual Provisions	15,700
Deferred Tax Assets, Valuation Allowance	(562,720)		$ (580,100)
Deferred Tax Assets, (Increase) Decrease in Valuation Allowance	$ 17,369	$ (110,679)