Common Stock - Summary of Stock Option Transactions during 2012 under 2010 Plan (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Schedule Of Stock Options [Line Items]
Outstanding balance, Number of Shares	3,529
Outstanding balance at Dec. 31, 2012, Number of Shares	2,087
Outstanding balance , Weighted Avg. Option Price (per share)	$ 15.05
Outstanding balance at Dec. 31, 2012, Weighted Avg. Remaining Contractual Term	2 years
Stock Options [Member]
Schedule Of Stock Options [Line Items]
Granted, Number of Shares	0
Exercised, Number of Shares	(78)
Cancelled, Number of Shares	(1,364)
Outstanding balance at Dec. 31, 2012, Number of Shares	2,087
Exercisable at Dec. 31, 2012, Number of Shares	2,087
Available for future grant at Dec. 31, 2012, Number of Shares	2,978
Outstanding balance , Weighted Avg. Option Price (per share)	$ 20.01
Granted, Weighted Avg. Option Price	$ 0.00
Exercised, Weighted Avg. Option Price	$ 13.52
Cancelled, Weighted Avg. Option Price	$ 27.97
Outstanding balance , Weighted Avg. Option Price (per share)	$ 15.05
Exercisable at Dec. 31, 2012, Weighted Avg. Option Price	$ 15.05
Outstanding balance at Dec. 31, 2012, Weighted Avg. Remaining Contractual Term	2 years
Exercisable at Dec. 31, 2012, Weighted Avg. Remaining Contractual Term	2 years
Outstanding balance at Dec. 31, 2012, Aggregate Intrinsic Value	$ 3.6
Exercisable at Dec. 31, 2012, Aggregate Intrinsic Value	$ 3.6