Income Taxes (Reconciliation of Effective Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal benefit	(14.20%)	(5.30%)	2.00%
Non-U.S. income taxed at different rates	(11.60%)	1.20%	(4.40%)
Impact of 2017 Tax Cuts and Jobs Act	(1.736)	0.000	0.000
Net operating loss carryback adjustment	(0.00%)	10.00%	1.40%
Reduction in tax benefit related to stock-based awards	(47.20%)	0.00%	0.00%
Non-deductible expenditures	(11.00%)	13.10%	5.90%
Research and development credit	10.80%	(12.70%)	(3.50%)
Other	1.80%	(2.00%)	(3.70%)
Effective income tax rate	(210.00%)	39.30%	32.70%