Equity-Based Compensation - Schedule of Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Options
Beginning balance (shares)	3,531,359
Granted (shares)	1,184,880
Exercised (shares)	(153,601)
Expired and/or forfeited (shares)	(846,059)
Ending balance (shares)	3,716,579	3,531,359
Outstanding at end of year - vested and unvested expected to vest (shares)	3,601,519
Exercisable at end of year (shares)	1,928,239
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 28.27
Granted (in dollars per share)	21.14
Exercised (in dollars per share)	19.26
Expired and/or forfeited (in dollars per share)	35.13
Ending balance (in dollars per share)	24.81	$ 28.27
Outstanding at end of year - vested and unvested expected to vest (in dollars per share)	24.92
Exercisable at end of year (in dollars per share)	$ 27.26
Stock Option Activity, Additional Disclosures
Weighted Average Remaining Contractual Term, Outstanding	7 years 3 months 18 days	7 years 2 months 12 days
Weighted Average Remaining Contractual Term, Outstanding at end of year - vested and unvested expected to vest	7 years 2 months 12 days
Weighted Average Remaining Contractual Term, Exercisable at end of year	5 years 9 months 18 days
Aggregate Intrinsic Value, Outstanding at end of year	$ 694
Aggregate Intrinsic Value, Outstanding at end of year, vested and unvested expected to vest	690
Aggregate Intrinsic Value, Exercisable at end of year	$ 515