Components of Other Operating Income (Detail) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of Other Operating Income [Line Items]
Loan Service Fees			$ 56.6	$ 59.1	$ 62.7
Banking Service Fees			50.6	48.2	49.6
Other Income			134.0	139.8	41.2
Total Other Operating Income			241.2	247.1	$ 153.5
Visa Class B
Components of Other Operating Income [Line Items]
Net gain on sale of derivative	$ 123.1	$ 99.9	$ 123.1	$ 99.9
Shares sold	1,100,000	1,000,000	1,100,000.0	1,000,000.0