Assets Measured at Fair Value on a Nonrecurring Basis (Parenthetical) (Detail) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Provision for Credit Losses	$ 17.5	$ 30.0	$ 42.5	$ 120.0
Other Operating Expenses	62.0	62.9	192.9	193.7
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Nonrecurring | Loans | Specific Reserve
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Provision for Credit Losses	3.0	1.7	10.5	16.1
Other Operating Expenses	$ 1.7	$ 2.6	$ 1.8	$ 3.8