Reconciliation of Total Provision for Income Taxes with Amount Computed at Statutory Federal Tax Rate (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Tax at Statutory Rate	$ 512.7	$ 416.6	$ 376.4
Tax Exempt Income	(4.8)	(4.9)	(6.2)
Leveraged Lease Adjustments	0.1	(3.4)	(2.3)
Foreign Tax Rate Differential	(44.2)	(44.1)	(27.6)
State Taxes, net	33.0	29.6	26.3
Other	(5.6)	(15.4)	(22.4)
Provision for Income Taxes	$ 491.2	$ 378.4	$ 344.2