Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Statutory rate		35.00%	35.00%	35.00%
Future enacted statutory rate					21.00%
Provisional net income tax benefit due to Tax Cuts and Jobs Act	$ 51,600
Provisional income tax benefit due to remeasurement of deferred taxes	59,700
Provisional income tax expense due to transition tax on foreign earnings	8,100
Decrease in deferred tax assets due to deemed mandatory repatriation	8,100
Valuation allowance	12,337	$ 12,337	$ 3,771
Undistributed earnings of foreign subsidiaries	48,000	48,000
Unrecognized tax benefits	318	318	343	$ 0		$ 0
Income tax refunds			$ 28,400
U.S. [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	115,800	115,800
Valuation allowance	3,000	3,000
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	3,900	3,900
Valuation allowance	$ 9,400	$ 9,400