Fair Value of Pension Plan Assets (Detail) - U.S. Plan - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 1,342.0	$ 1,440.8	$ 1,342.1
COMMON STOCK | U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	45.4
COMMON STOCK | Non U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0.3
Preferred and Common Stock | U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		14.8
Fixed Income | U.S. Government Sponsored Agency
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	135.7	159.5
Other Investment | Mutual Funds | Global Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	64.3
Other Investment | Mutual Funds | Foreign Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		69.6
Other Investment | Exchange Traded Funds | Domestic Large Cap Core
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0.5
Other Investment | Collective Trust Fund | Foreign Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	113.0	105.4
Other Investment | Collective Trust Fund | Foreign Small Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	37.1	37.2
Other Investment | Collective Trust Fund | Domestic Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		196.7
Other Investment | Collective Trust Fund | Domestic Small Cap Value
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	104.9	26.5
Other Investment | Collective Trust Fund | Domestic Mid Cap Value
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		14.4
Other Investment | Collective Trust Fund | Domestic Small Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	15.0	21.2
Other Investment | Collective Trust Fund | Domestic Large Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	36.6
Other Investment | Collective Trust Fund | Domestic Large Cap Minimum Volatility
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	82.4
Other Investment | Collective Trust Fund | Domestic Mid Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		15.2
Other Investment | Collective Trust Fund | Short-Term Investment
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	5.5	3.4
Other Investment | Collective Trust Fund | Global Real Estate Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	67.0	73.8
Other Investment | Collective Trust Fund | Domestic Long-Term Bond
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	464.3	508.0
Other Investment | Collective Trust Fund | Emerging Market Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	59.1	68.2
Other Investment | Private Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	47.5	49.0
Other Investment | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	63.4	68.6
Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		9.3
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	110.5	93.7
Fair Value, Inputs, Level 1 | COMMON STOCK | U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	45.4
Fair Value, Inputs, Level 1 | COMMON STOCK | Non U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0.3
Fair Value, Inputs, Level 1 | Preferred and Common Stock | U.S.
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		14.8
Fair Value, Inputs, Level 1 | Other Investment | Mutual Funds | Global Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	64.3
Fair Value, Inputs, Level 1 | Other Investment | Mutual Funds | Foreign Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		69.6
Fair Value, Inputs, Level 1 | Other Investment | Exchange Traded Funds | Domestic Large Cap Core
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	0.5
Fair Value, Inputs, Level 1 | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		9.3
Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	1,120.6	1,229.5
Fair Value, Inputs, Level 2 | Fixed Income | U.S. Government Sponsored Agency
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	135.7	159.5
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Foreign Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	113.0	105.4
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Foreign Small Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	37.1	37.2
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		196.7
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Small Cap Value
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	104.9	26.5
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Mid Cap Value
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		14.4
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Small Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	15.0	21.2
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Large Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	36.6
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Large Cap Minimum Volatility
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	82.4
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Mid Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value		15.2
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Short-Term Investment
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	5.5	3.4
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Global Real Estate Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	67.0	73.8
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Domestic Long-Term Bond
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	464.3	508.0
Fair Value, Inputs, Level 2 | Other Investment | Collective Trust Fund | Emerging Market Large Cap Blend
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	59.1	68.2
Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	110.9	117.6
Fair Value, Inputs, Level 3 | Private Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	47.5	49.0	47.7
Fair Value, Inputs, Level 3 | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	63.4	68.6	$ 55.1
Fair Value, Inputs, Level 3 | Other Investment | Private Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	47.5	49.0
Fair Value, Inputs, Level 3 | Other Investment | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Total Assets at Fair Value	$ 63.4	$ 68.6