Stock-Based Compensation - Summary of Stock Option and SAR Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Number of Stock Awards
Exercised (in shares)		0
Weighted- Average Exercise Price
Aggregate Intrinsic Value of Awards, Exercisable	$ 600
Stock Options and SARs [Member]
Number of Stock Awards
Beginning Balance (in shares)	4,691,000
Granted at market value (in shares)	0
Exercised (in shares)	(118,000)
Forfeited or expired (in shares)	(62,000)
Ending Balance (in shares)	4,511,000
Exercisable (in shares)	1,685,000
Available for future grants (in shares)	15,370,000
Weighted- Average Exercise Price
Beginning Balance (in dollars per share)	$ 17.41
Granted at market value (in dollars per share)	0.00
Exercised (in dollars per share)	8.24
Forfeited or expired (in dollars per share)	29.12
Ending Balance (in dollars per share)	17.49
Exercisable (in dollars per share)	$ 21.11
Aggregate Intrinsic Value of Awards, Outstanding	$ 4,524
Aggregate Intrinsic Value of Awards, Exercisable	$ 1,418
Weighted-Average Remaining Life, Outstanding	2 years 10 months 27 days
Weighted-Average Remaining Life, Exercisable	2 years 9 months 14 days
SARs [Member]
Number of Stock Awards
Beginning Balance (in shares)	1,700,000
Ending Balance (in shares)	1,700,000