Changes in Allowance for Credit Losses by Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	$ 329.9	$ 345.8	$ 328.9	$ 357.3
Charge-Offs	(16.3)	(34.9)	(46.9)	(87.5)
Recoveries	4.4	6.3	26.0	22.3
Net (Charge-Offs) Recoveries	(11.9)	(28.6)	(20.9)	(65.2)
Provision for Credit Losses	10.0	17.5	20.0	42.5
Effect of Foreign Exchange Rates		(0.1)
Balance at End of Period	328.0	334.6	328.0	334.6
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	196.3	239.9	211.0	256.7
Charge-Offs	(7.2)	(16.8)	(15.4)	(45.0)
Recoveries	2.4	4.4	13.6	17.5
Net (Charge-Offs) Recoveries	(4.8)	(12.4)	(1.8)	(27.5)
Provision for Credit Losses	6.9	(6.4)	(10.8)	(8.2)
Effect of Foreign Exchange Rates		(0.1)
Balance at End of Period	198.4	221.0	198.4	221.0
Personal
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	133.6	105.9	117.9	100.6
Charge-Offs	(9.1)	(18.1)	(31.5)	(42.5)
Recoveries	2.0	1.9	12.4	4.8
Net (Charge-Offs) Recoveries	(7.1)	(16.2)	(19.1)	(37.7)
Provision for Credit Losses	3.1	23.9	30.8	50.7
Balance at End of Period	$ 129.6	$ 113.6	$ 129.6	$ 113.6