Allocation of Plan Assets by Investments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	$ 2,219.0	$ 2,309.4	$ 2,108.4
Equity Funds
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Equity funds, target minimum	50.00%	50.00%
Equity funds, target maximum	70.00%	70.00%
Plan assets	$ 1,268.0	$ 1,357.7
Equity Funds | United States
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	593.8	666.4
Equity Funds | Global
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	$ 674.2	$ 691.3
Fixed Income Funds
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Equity funds, target minimum	30.00%	30.00%
Equity funds, target maximum	50.00%	50.00%
Plan assets	$ 885.3	$ 895.1
Fixed Income Funds | United States
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	631.6	608.6
Fixed Income Funds | Non U.S.
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	253.7	286.5
Cash and other
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	65.7	56.6
Level 1
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	291.6	277.1
Level 1 | Fixed Income Funds
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	283.4	269.4
Level 1 | Fixed Income Funds | United States
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	283.4	269.4
Level 1 | Cash and other
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	8.2	7.7
Level 2
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	1,927.4	2,032.3
Level 2 | Equity Funds
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	1,268.0	1,357.7
Level 2 | Equity Funds | United States
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	593.8	666.4
Level 2 | Equity Funds | Global
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	674.2	691.3
Level 2 | Fixed Income Funds
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	601.9	625.7
Level 2 | Fixed Income Funds | United States
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	348.2	339.2
Level 2 | Fixed Income Funds | Non U.S.
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	253.7	286.5
Level 2 | Cash and other
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Plan assets	$ 57.5	$ 48.9