Income Taxes Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Tax Cuts And Jobs Act Of 2017, Income tax benefit	$ (139,400)
Income tax valuation allowance	0	$ 286
Unremitted earnings	47,000
Taxes withhelld on unremitted earnings	14,000
Unrecognized tax benefits with no impact on after-tax income	6,900
Decrease in unrecognized tax benefits that is reasonably possible in the next twelve months	1,400
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	700,000
United States
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 926,700