Equity-Based Compensation - Schedule of Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Options
Beginning balance (shares)	3,113,178
Granted (shares)	1,145,992
Exercised (shares)	(92,529)
Expired or forfeited (shares)	(635,282)
Ending balance (shares)	3,531,359
Options to purchase shares of common stock
Options
Outstanding at end of year - vested and unvested expected to vest (shares)		3,267,530
Exercisable at end of year (shares)		1,871,179
Weighted Average Exercise Price
Beginning balance (USD per share)	$ 28.27	$ 28.27	$ 31.97
Granted (USD per share)	20.11
Exercised (USD per share)	15.39
Expired and/or forfeited (USD per share)	33.56
Ending balance (USD per share)	$ 28.27
Outstanding at end of year - vested and unvested expected to vest (USD per share)		28.37
Exercisable at end of year (USD per share)		$ 29.33
Stock Option Activity, Additional Disclosures
Weighted Average Remaining Contractual Term, Outstanding	7 years 2 months
Weighted Average Remaining Contractual Term, Outstanding at end of year - vested and unvested expected to vest (in years)	7 years 1 month
Weighted Average Remaining Contractual Term, Exercisable at end of year	5 years 9 months
Aggregate Intrinsic Value, Outstanding at end of year		$ 55
Aggregate Intrinsic Value, Outstanding at end of year, vested and unvested expected to vest		55
Aggregate Intrinsic Value, Exercisable at end of year		$ 55