Share-Based Compensation - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance (shares)	2,684,650
Granted (shares)	145,000
Forfeited (shares)	(73,500)
Exercised (shares)	(36,330)
Ending balance (shares)	2,719,820
Exercisable at end of period (shares)	977,250
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning balance, weighted average exercise price (dollars per share) | $ / shares	$ 14.70
Granted, weighted average exercise price (dollars per share) | $ / shares	20.70
Forfeited, weighted average exercise price (dollars per share) | $ / shares	14.07
Exercised, weighted average exercise price (dollars per share) | $ / shares	13.99
Ending balance, weighted average exercise price (dollars per share) | $ / shares	15.04
Exercisable at end of period, weighted average exercise price (dollars per share) | $ / shares	$ 14.38
Outstanding, weighted average remaining contractual term (years)	7 years 9 months 4 days
Exercisable at period end, weighted average remaining contractual term (years)	7 years 3 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercised, aggregate intrinsic value | $	$ 255,000
Outstanding, aggregate intrinsic value | $	15,794,000
Exercisable, aggregate intrinsic value | $	$ 6,327,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Granted (shares)	145,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Unrecognized compensation cost | $	$ 6,692,000
Weighted average remaining recognition period (years)	3 years 18 days