Stock-Based Compensation - Summary of Stock Option and SAR Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Number of Stock Awards
Exercised (in shares)	(1,800)	0	(1,800)	0
Stock options and SARs
Number of Stock Awards
Beginning Balance (in shares)			4,371,000
Granted (in shares)			2,059,000
Exercised (in shares)			(2,000)
Forfeited or expired (in shares)			(61,000)
Ending Balance (in shares)	6,367,000		6,367,000
Exercisable (in shares)	4,308,000		4,308,000
Available for future grants (in shares)	13,073,000		13,073,000
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)			48.38
Ending Balance (in dollars per share)	$ 18.96		18.96
Exercisable (in dollars per share)	$ 16.92		$ 16.92
Aggregate Intrinsic Value, Outstanding	$ 11,818		$ 11,818
Aggregate Intrinsic Value, Exercisable			$ 11,818
Weighted-Average Remaining Life, Outstanding			2 years 6 months 28 days
Weighted-Average Remaining Life, Exercisable			1 year 7 months 28 days
SARs
Number of Stock Awards
Beginning Balance (in shares)			1,700,000
Ending Balance (in shares)	1,700,000		1,700,000