Share-Based Compensation - Summary of Activity for Stock Options Granted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Shares at Beginning of Year	3,010,233	2,363,728	2,726,553
Number of Shares Granted	1,272,293	789,210	67,507
Number of Shares Exercised	(64,220)	(15,458)	(303,449)
Number of Shares Forfeited or Expired	(311,309)	(127,247)	(126,883)
Number of Shares at End of Year	3,906,997	3,010,233	2,363,728	2,726,553
Number of Shares Exercisable	2,471,233
Number of Shares, Options expected to vest	1,355,723
Weighted Average Exercise Price Per Share, Beginning of Year	$ 21.87	$ 23.95	$ 23.51
Weighted Average Exercise Price Per Share, Shares Granted	5.69	16.39	29.11
Weighted Average Exercise Price Per Share, Share Exercised	2.89	12.88	18.12
Weighted Average Exercise Price Per Share, Shares Forfeited or expired	16.51	27.66	31.24
Weighted Average Exercise Price Per Share, End of Year	17.34	$ 21.87	$ 23.95	$ 23.51
Weighted Average Exercise Price Per Share, Shares Exercisable	22.69
Weighted Average Exercise Price Per Share, Options expected to vest	$ 8.14
Weighted Average Remaining Contractual Term, End of Year	5 years 8 months 27 days	5 years 6 months 23 days	6 years 4 months 2 days	7 years 2 months 19 days
Weighted Average Remaining Contractual Term, Shares Exercisable	4 years 5 months 1 day
Weighted Average Remaining Contractual Term, Options expected to vest	7 years 11 months 12 days
Aggregate Intrinsic Value, Shares Exercised	$ 200	$ 150	$ 3,468
Aggregate Intrinsic Value, End of Year	1,809	$ 443	$ 1,223	$ 32,785
Aggregate Intrinsic Value, Shares Exercisable	119
Aggregate intrinsic Value, Options expected to vest	$ 1,577