Income Taxes - Effective Income Tax Rate on Income Before Income Taxes (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. statutory tax rate	35.00%	35.00%	35.00%
Non-U.S. income taxed at other than 35%	(0.10%)	(0.30%)	(0.80%)
State and local income taxes	3.50%	2.50%	1.10%
U.S. tax on non-U.S. earnings	7.30%	(15.40%)	7.80%
Valuation allowance	1.10%	7.80%	1.20%
Tax credits and incentives	(11.20%)	(12.40%)	(8.40%)
U.S. federal tax reform impact	(23.40%)	0.00%	0.00%
Other	(1.30%)	0.00%	(1.50%)
Effective tax rate	10.90%	17.20%	34.40%