Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 12.7
Period of expense of unrecognized compensation cost, years	3 years
Common stock reserved for future issuance (in shares)	3,400,000
Shares available for future grant (in shares)	800,000
Maximum term of grants	10 years
Options vested and exercisable, period	5 years
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 8.52	$ 7.46
Aggregate intrinsic value of stock options exercised	$ 13.3	$ 4.6
Supplemental Employee Retirement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares)	1,000,000
Remaining shares authorized for issuance (in shares)	400,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted (in shares)	0	44,000
Weighted average grant date fair value of restricted stock granted (in dollars per share)	$ 0.00	$ 34.14
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted (in shares)	88,000	0
Weighted average grant date fair value of restricted stock granted (in dollars per share)	$ 40.16
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant (in shares)	2,300,000
Average weekly hours of work	20 hours
Requisite service period for plan participation eligibility	2 years
Stock options authorized to issue to employees (in shares)	4,100,000