Share-Based Compensation - Compensation Awards (Details) - 2013 EIP and 2014 NEEIP - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Shares Subject To Outstanding Options
Balance at the beginning of the year	3,299,179
Granted ( in shares)	230,750
Exercised (in shares)	(275)
Forfeited (in shares)	(658,086)
Balance at the end of the year	2,871,568	3,299,179
Weighted-Average Exercise Price of Outstanding Options
Balance at the beginning of the year (in dollars per share)	$ 24.58
Granted (in dollars per share)	18.85
Exercised (in dollars per share)	16.76
Forfeited (in dollars per share)	22.41
Balance at the end of the year (in dollars per share)	$ 24.62	$ 24.58
Additional disclosures
Weighted-Average Remaining Contractual Term (Years), Outstanding	4 years 7 months 17 days
Weighted-Average Remaining Contractual Term (Years), Exercisable	3 years 11 months 12 days
Weighted-Average Remaining Contractual Term (Years), Vested and expected to vest	4 years 7 months 13 days
Aggregate intrinsic value of options outstanding	$ 1,070
Aggregate intrinsic value of options exercisable	$ 867
Weighted-average estimated fair value (in dollars per share)	$ 9.25	$ 11.03	$ 10.20
Aggregate intrinsic value of vested or expected to vest	$ 1,070
Total intrinsic value of options exercised	$ 1	$ 384	$ 822