Income Taxes (Reconciliation of the Company's Effective Tax Rate to the Statutory Federal Rate) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal statutory taxes	35.00%	35.00%	35.00%
State income taxes, net of federal tax benefit	2.10%	0.80%	(1.00%)
Foreign operations	(20.00%)	(21.60%)	(41.10%)
Permanent differences	2.60%	3.20%	13.90%
The 2017 Tax Act - tax rate impact on deferred taxes	11.80%	0.00%	0.00%
The 2017 Tax Act - transition tax	66.30%	0.00%	0.00%
Change in valuation allowance reserve	8.80%	0.00%	0.00%
Change in deferred tax liability related to acquired intangibles	0.30%	(0.80%)	(12.60%)
Tax credits	(7.60%)	(7.90%)	(20.70%)
Stock-based compensation	(3.60%)	0.30%	0.80%
Change in accruals for uncertain tax positions	0.30%	2.20%	(5.90%)
Other	0.00%	(0.20%)	0.90%
Effective income tax rate	96.00%	11.00%	(30.70%)