Changes in Allowance for Credit Losses by Segment (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	$ 286.7	$ 309.4	$ 295.9	$ 307.9
Charge-Offs	(6.1)	(7.8)	(13.6)	(19.3)
Recoveries	3.5	1.9	6.4	11.9
Net (Charge-Offs) Recoveries	(2.6)	(5.9)	(7.2)	(7.4)
Provision for Credit Losses	(10.0)		(14.5)	3.0
Effect of Foreign Exchange Rates	0.1
Balance at End of Period	274.2	303.5	274.2	303.5
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	164.3	173.1	169.7	168.0
Charge-Offs	(2.5)	(2.1)	(5.2)	(6.3)
Recoveries	2.4	0.3	4.1	8.8
Net (Charge-Offs) Recoveries	(0.1)	(1.8)	(1.1)	2.5
Provision for Credit Losses	(11.6)	(2.6)	(15.9)	(1.8)
Effect of Foreign Exchange Rates	0.1
Balance at End of Period	152.7	168.7	152.7	168.7
Personal
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at Beginning of Period	122.4	136.3	126.2	139.9
Charge-Offs	(3.6)	(5.7)	(8.4)	(13.0)
Recoveries	1.1	1.6	2.3	3.1
Net (Charge-Offs) Recoveries	(2.5)	(4.1)	(6.1)	(9.9)
Provision for Credit Losses	1.6	2.6	1.4	4.8
Balance at End of Period	$ 121.5	$ 134.8	$ 121.5	$ 134.8