Subsequent Event - Additional Information (Detail) (Subsequent Event [Member], USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	9 Months Ended
	Oct. 31, 2012	Sep. 29, 2012
Subsequent Event [Member]
Subsequent Event [Line Items]
Common stock dividend declared per share	$ 1.00
Dividends payable date		Dec. 11, 2012
Dividends payable recorded date		Nov. 27, 2012
Total dividend payout	$ 57.2