Income Taxes Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, period increase (decrease)			$ (88)	$ (3,335)
Income tax expense	$ 1,679	$ (204)	$ 6,027	$ 363
United States
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%