Postretirement Health Care Plan Net Periodic (Benefit) Expense (Detail) - Other Postretirement Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 0.1	$ 0.1	$ 0.1
Interest Cost	1.4	1.5	1.2
Amortization
Net Gain	0.0	0.6	1.2
Prior Service Benefit	0.0	0.0	(3.0)
Net Periodic Pension Expense (Benefit)	$ 1.5	$ 1.0	$ (2.9)