Per Common Share Information (Additional Information) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Earnings Per Share [Abstract]
Dilutive effect of share-based compensation	6.9	9.3	7.7	10.6
Dividends Payable, Current	$ 803.0		$ 803.0		$ 0
Dividends Payable, Amount Per Share	$ 0.81		$ 0.81
Stock options that were not included in diluted weighted-average shares	7.7	4.7	4.7	4.7