Summary of Post-Retirement Plans to Amortize from Accumulated Other Comprehensive Income (Loss) as Net Periodic Expense (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Pension Plans [Member]
Schedule Of Net Periodic Benefit Costs And Assumptions For Defined Benefit Retirement Plans [Line Items]
Net actuarial losses	$ 10.3
Net prior service costs	0.1
Total to be recognized as components of net periodic expense	10.4
Other Retirement Plans [Member]
Schedule Of Net Periodic Benefit Costs And Assumptions For Defined Benefit Retirement Plans [Line Items]
Net actuarial losses	0.2
Net prior service costs	(0.3)
Total to be recognized as components of net periodic expense	$ (0.1)