Stock-Based Compensation (Assump) (Details) - $ / shares	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Summary of weighted average assumptions used to value options granted
Grant date fair value of options (in dollars per share)	$ 14.46	$ 9.56	$ 20.90
Volatility (as a percent)	42.20%	42.20%	37.20%
Risk-free interest rate (as a percent)	1.10%	1.40%	1.70%
Expected term (in years)	5 years	6 years 3 months 18 days	6 years