Stock-based Compensation - Stock Option Activity (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Jun. 30, 2015 $ / shares	Dec. 31, 2015 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding at December 31, 2014 (in shares) | shares		5,262,914
Options, Granted (in shares) | shares		1,297,772
Options, Exercised (in shares) | shares		(47,835)
Options, Expired (in shares) | shares		(157,402)
Options, Forfeited (in shares) | shares		(58,660)
Options, Outstanding at December 31, 2015 (in shares) | shares		6,296,789
Options, Exercisable at December 31, 2015 (in shares) | shares		4,648,885
Options, Expected to vest (in shares) | shares		6,034,302
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-Average Exercise Price, Outstanding at December 31, 2014 (in dollars per share) | $ / shares		$ 6.64
Weighted-Average Exercise Price, Granted (in dollars per share) | $ / shares	$ 20.00	19.62
Weighted-Average Exercise Price, Exercised (in dollars per share) | $ / shares		6.64
Weighted-Average Exercise Price, Expired (in dollars per share) | $ / shares		6.64
Weighted-Average Exercise Price, Forfeited (in dollars per share) | $ / shares		8.50
Weighted-Average Exercise Price, Outstanding at December 31, 2015 (in dollars per share) | $ / shares		9.30
Weighted-Average Exercise Price, Exercisable at December 31, 2015 (in dollars per share) | $ / shares		6.64
Weighted-Average Exercise Price, Expected to vest (in dollars per share) | $ / shares		$ 8.86
Weighted-Average Remaining Contractual Term, Outstanding at December 31, 2015		7 years 8 months 12 days
Weighted-Average Remaining Contractual Term, Exercisable at December 31, 2015		7 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Expected to vest		7 years 7 months 6 days
Aggregate Intrinsic Value, Outstanding at December 31, 2015 | $		$ 29.6
Aggregate Intrinsic Value, Exercisable at December 31, 2015 | $		27.3
Aggregate Intrinsic Value, Expected to vest | $		$ 29.5