Changes in Allowance for Credit Losses by Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	$ 328.9	$ 357.3
Charge-Offs	(14.4)	(35.4)
Recoveries	8.6	13.8
Net Charge-Offs	(5.8)	(21.6)
Provision for Credit Losses	5.0	15.0
Effect of Foreign Exchange Rates		0.1
Balance at End of Period	328.1	350.8
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	211.0	256.7
Charge-Offs	(3.2)	(20.7)
Recoveries	3.7	12.8
Net Charge-Offs	0.5	(7.9)
Provision for Credit Losses	(9.5)	(1.9)
Effect of Foreign Exchange Rates		0.1
Balance at End of Period	202.0	247.0
Personal
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	117.9	100.6
Charge-Offs	(11.2)	(14.7)
Recoveries	4.9	1.0
Net Charge-Offs	(6.3)	(13.7)
Provision for Credit Losses	14.5	16.9
Balance at End of Period	$ 126.1	$ 103.8