Equity-Based Compensation (Details) $ / shares in Units, $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($) item $ / shares shares	Jun. 30, 2014 USD ($)	Dec. 31, 2014 $ / shares shares	Apr. 30, 2014 $ / shares
Equity based compensation
Number of vesting triggers | item	2
Service period	5 years
2014 Plan
Equity based compensation
Number of shares authorized	8,603,066
Shares issued under plan	1,246,384
Stock options
Common stock options
Outstanding at the beginning of the period (in shares)	449,046
Options exercised (in shares)	(109,562)
Repurchased (in shares)	9,028
Options forfeited/cancelled (in shares)	(2,336)
Outstanding at the end of the period (in shares)	337,148		449,046
Exercisable at the end of the period (in shares)	327,865
Expected to vest at the end of the period (in shares)	5,896
Weighted Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 2.98
Exercised (in dollars per share) | $ / shares	2.96
Forfeited/canceled (in dollars per share) | $ / shares	3.23
Outstanding at the end of the period (in dollars per share) | $ / shares	2.98		$ 2.98
Exercisable at the end of the period (in dollars per share) | $ / shares	2.97
Expected to vest at the end of the period (in dollars per share) | $ / shares	$ 3.32
Weighted-Average Remaining Contractual Term (Years)
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	6 years		6 years 6 months
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	6 years		6 years 6 months
Exercisable at the end of the period	6 years
Expected to vest at the end of the period	6 years
Additional disclosures
Aggregate intrinsic value of stock options exercised | $	$ 2.8
Aggregate intrinsic value of stock options outstanding and repurchased | $	11.7
Aggregate intrinsic value of stock options exercisable | $	11.4
Unrecognized share-based compensation | $	$ 0.1
Weighted average remaining vesting term for options expected to vest	3 months 18 days
Restricted stock
Common stock options
Repurchased (in shares)	202,757
Common stock options and restricted common stocks
Equity based compensation
Share based compensation expenses | $		$ 5.5
Weighted-Average Remaining Contractual Term (Years)
Tender offer price per unit | $ / shares				$ 26.23
Payments of repurchase of stock | $	$ 5.5
Compensation charge | $	$ 5.5