Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stock options, additional information
Fair value of the Company's common stock price (in dollars per share)	$ 23.33
Stock options
Stock options, Shares Subject to Options
Outstanding at the beginning of the period (in shares)	4,625,678
Granted (in shares)	10,430
Exercised (in shares)	(83,829)
Forfeited (in shares)	(69,772)
Outstanding at the end of the period (in shares)	4,482,507
Exercisable at the end of the period (in shares)	2,304,015
Exercisable and expected to vest at the end of the period (in shares)	4,336,330
Stock options, Weighted Average Option Price
Outstanding at the beginning of the period (in dollars per share)	$ 18.73
Granted (in dollars per share)	22.80
Exercised (in dollars per share)	14.41
Forfeited (in dollars per share)	17.73
Outstanding at the end of the period (in dollars per share)	18.83
Exercisable at the end of the period (in dollars per share)	16.42
Exercisable and expected to vest at the end of the period (in dollars per share)	$ 18.75
Stock options, additional information
Weighted Average Remaining Contractual Term, Outstanding	6 years 6 months
Weighted Average Remaining Contractual Term, Exercisable	5 years
Weighted Average Remaining Contractual Term, Exercisable and expected to vest	6 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding	$ 20.7
Aggregate Intrinsic Value, Exercisable	16.0
Aggregate Intrinsic Value, Exercisable and expected to vest	$ 20.3
Weighted average fair values of options granted (in dollars per share)	$ 7.40	$ 9.98
Intrinsic value of options exercised	$ 0.8	$ 7.5