Income Taxes - Reconciliation of the Difference between the Actual Provisions for Income Taxes (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory federal income tax rate	21.00%	35.00%	35.00%
State income taxes	1.60%	1.60%	2.10%
Valuation allowances for deferred tax assets, including state	(1.30%)	0.10%	1.30%
Research and development credits	(1.30%)	(1.00%)	(1.20%)
Capitalized transaction costs	0.60%	0.00%	0.70%
Domestic production activities deduction	(0.00%)	(1.80%)	(2.70%)
Stock based compensation	(0.70%)	(4.40%)	(2.10%)
German Cartel settlement	0.00%	0.00%	2.20%
Foreign income taxed at lower rates	(1.60%)	(2.80%)	(3.50%)
Reserves for uncertain tax positions	0.00%	(1.70%)	(0.10%)
Repatriation of foreign undistributed earnings	1.60%	1.30%	0.00%
Revaluation of deferred tax liabilities due to federal rate change	0.00%	(7.30%)	0.00%
Other	(0.40%)	0.50%	0.70%
Effective income tax rate	19.50%	19.50%	32.40%