Significant Accounting Policies - Revised Balance Sheet (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Paid-in capital	$ 8,293.6	$ 8,230.6	$ 8,195.3
Retained earnings	$ 8,331.9	8,410.4	$ 8,347.7
As Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Paid-in capital		8,233.5
Retained earnings		8,407.5
Adjustments [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Paid-in capital		(2.9)
Retained earnings		$ 2.9