Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation
Tax at federal statutory rate (as a percent)	35.00%	35.00%	34.00%
Permanent differences (as a percent)	(1.60%)	(2.90%)	(1.70%)
State income taxes (as a percent)	2.00%	3.10%	4.80%
Foreign taxes (as a percent)	0.30%	2.50%	(1.60%)
Other (as a percent)	0.60%	1.40%	2.90%
Effective income tax rate (as a percent)	36.30%	39.10%	38.40%