Income Taxes Effective tax rate (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	$ 51,283	$ 85,164	$ 69,699
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	17,950	29,807	24,395
Income Tax Reconciliation, State and Local Income Taxes	(403)	1,795	2,661
Income Tax Reconciliation, Tax Credits	(2,783)	(1,014)	(5,861)
Income Tax Reconciliation, Foreign Income Tax Rate Differential	$ 3,481	$ (135)	$ 3,412
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes	(0.80%)	2.10%	3.90%
Effective Income Tax Rate Reconciliation, Tax Credits	(5.40%)	(1.20%)	(8.40%)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential	6.80%	0.10%	(4.90%)
Effective Income Tax Rate, Continuing Operations	(33.80%)	25.90%	35.50%
effective income tax rate reconciliation, ASU 2016-09	$ (18,958)	$ (7,720)	$ 0
effective income tax rate reconciliation-percent, ASU 2016-09	(37.00%)	(9.10%)	(0.00%)
Tax reform	$ 3,076	$ 0	$ 0
EffectiveIncomeTaxRateREconciliationTaxReform	0.060	0.000	0.000
EffectiveIncomeTaxRateReconciliationIPMigration	$ 3,367	$ 0	$ 0
EffectiveTaxRateReconciliationIPMigrationPercent	0.066	0.000	0.000
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	$ 1,720	$ (653)	$ 107
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent	3.40%	(0.80%)	0.10%
EffectiveIncomeTaxRateReconciliationBargainPurchaseGain	$ (24,811)	$ 0	$ 0
EffectiveTaxRateReconciliationBargainPurchaseGainPercent	(0.484)	0.000	0.000