Income Taxes Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%	35.00%	35.00%
Income Tax Expense (Benefit)	$ (50,092)	$ (166,008)	$ (159,241)
Tax Cuts and Jobs Act 2017 [Member]
Income Tax Contingency [Line Items]
Other Tax Expense (Benefit)	$ 3,200
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Income Tax Expense (Benefit)	$ 120,900
Taxes Payable	3,300
Deferred Tax Liabilities, Deferred Expense	$ 124,166