Changes in Level 3 U.S. Pension Plan Assets (Detail) (U.S. Plan, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair Value at beginning of year	$ 1,342.1	$ 1,277.7
Actual Return on Plan Assets	157.1	122.1
Fair Value at end of year	1,440.8	1,342.1
Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair Value at end of year	117.6	102.8
Fair Value, Inputs, Level 3 | Private Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value at beginning of year	47.7	47.4
Actual Return on Plan Assets	10.3	5.5
Purchases	3.5	6.2
Sales	(12.5)	(11.4)
Fair Value at end of year	49.0	47.7
Fair Value, Inputs, Level 3 | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value at beginning of year	55.1	30.2
Actual Return on Plan Assets	1.8	4.9
Realized Gain	1.7
Purchases	15.0	20.0
Sales	(5.0)
Fair Value at end of year	$ 68.6	$ 55.1