Stock-Based Compensation - Summary of Stock Option and SAR Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Weighted- Average Exercise Price
Aggregate Intrinsic Value, Exercisable | $	$ 2,200
Stock options and SARs
Number of Stock Awards
Beginning Balance (in shares)	6,298
Granted (in shares)	0
Exercised (in shares)	(337)
Forfeited or expired (in shares)	(94)
Ending Balance (in shares)	5,867
Exercisable (in shares)	4,492
Available for future grants (in shares)	13,630
Weighted- Average Exercise Price
Beginning Balance (in dollars per share) | $ / shares	$ 18.88
Granted (in dollars per share) | $ / shares	0.00
Exercised (in dollars per share) | $ / shares	8.24
Forfeited or expired (in dollars per share) | $ / shares	53.56
Ending Balance (in dollars per share) | $ / shares	19.03
Exercisable (in dollars per share) | $ / shares	$ 17.75
Aggregate Intrinsic Value, Outstanding | $	$ 14,269
Aggregate Intrinsic Value, Exercisable | $	$ 14,269
Weighted-Average Remaining Life, Outstanding	2 years 2 months 24 days
Weighted-Average Remaining Life, Exercisable	1 year 8 months 10 days
SARs
Number of Stock Awards
Beginning Balance (in shares)	1,700