Stockholders' Equity (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015
Equity Incentive Plan
Exercised (in shares)	(985,583)	(1,462,369)	(876,115)
Stock Options
Equity Incentive Plan
Granted (in shares)	172,250
Exercised (in shares)	(984,583)
Expected volatility maximum period	5 years
Method and assumptions on valuation of stock options
Expected volatility (as a percent)	33.10%	32.60%
Risk-free interest rate (as a percent)	2.00%	1.70%
Expected term of options	5 years 9 months 18 days	5 years
Expected forfeiture rate (as a percent)	1.50%	0.00%
Expected dividend yield (as a percent)	0.00%	0.00%
Amended and Restated Equity Incentive Plan (The 1999 Plan)
Equity Incentive Plan
Granted (in shares)	0	0
Stock Incentive Plan 2015 (The 2015 Plan)
Equity Incentive Plan
Maximum number of shares authorized to be issued				6,150,000
Granted (in shares)	172,250	723,869