Financial Instruments Carried at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative contracts	$ 12.6	$ 41.8
Money Market Funds at Carrying Value	188.3	149.7
Fixed maturity and open ended mutual funds	31.9	48.0
Total, assets	232.8	239.5
Derivatives, liabilities	12.4	2.1
Contingent consideration arising from acquisitions, payment or settlement		2.1
Total, liabilities	12.4	4.2
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Money Market Funds at Carrying Value	188.3	149.7
Fixed maturity and open ended mutual funds	31.9	48.0
Total, assets	220.2	197.7
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative contracts	12.6	41.8
Total, assets	12.6	41.8
Derivatives, liabilities	12.4	2.1
Total, liabilities	$ 12.4	2.1
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent consideration arising from acquisitions, payment or settlement		2.1
Total, liabilities		$ 2.1