Stock-Based Compensation - Summary of Stock Option and SAR Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Weighted- Average Exercise Price
Aggregate Intrinsic Value, Exercisable	$ 300	$ 700
Stock options and SARs
Number of Stock Awards
Beginning Balance (in shares)	4,371
Granted (in shares)	2,059
Exercised (in shares)	(43)
Forfeited or expired (in shares)	(89)
Ending Balance (in shares)	6,298	4,371
Exercisable (in shares)	4,906
Available for future grants (in shares)	13,221
Weighted- Average Exercise Price
Beginning Balance (in dollars per share)	$ 17.36
Granted (in dollars per share)	23.35
Exercised (in dollars per share)	8.24
Forfeited or expired (in dollars per share)	49.64
Ending Balance (in dollars per share)	18.88	$ 17.36
Exercisable (in dollars per share)	$ 17.66
Aggregate Intrinsic Value, Outstanding	$ 6,224
Aggregate Intrinsic Value, Exercisable	$ 6,224
Weighted-Average Remaining Life, Outstanding	2 years 3 months 29 days
Weighted-Average Remaining Life, Exercisable	1 year 9 months 18 days
SARs
Number of Stock Awards
Beginning Balance (in shares)	0
Ending Balance (in shares)	1,700	0