Employee Benefit Plans - Schedule of Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Pension Plans
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Net actuarial gain (loss)	$ 0.3	$ (113.0)	$ 19.8
Plan curtailment			7.1
Plan settlement		(0.2)
Amortization of unrecognized prior service cost (credit)	0.4	0.5	1.1
Amortization of unrecognized prior service cost net transition obligations			0.4
Amortization of unrecognized net actuarial gain/loss	15.4	11.3	14.2
Total	16.1	(101.4)	42.6
OPEB
Pension Plans Postretirement And Other Employee Benefits [Line Items]
Net actuarial gain (loss)	0.8	(1.4)	2.2
Amortization of unrecognized prior service cost (credit)	(1.9)	(2.0)	(2.4)
Plan amendments/curtailment		(0.2)	4.5
Total	$ (1.1)	$ (3.6)	$ 4.3