Employee Benefit Plans - Components of Net Periodic Defined Benefit Pension Benefit Cost (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2.5	$ 3.2	$ 7.6	$ 9.7
Interest cost	6.3	6.0	19.0	17.9
Expected return on plan assets	(6.2)	(5.8)	(18.7)	(17.8)
Prior service cost	0.2	0.4	0.6	1.2
Net transition obligations		0.1		0.3
Recognized actuarial losses (gain)	2.8	3.4	8.4	10.2
Total	5.6	7.3	16.9	21.5
OPEB
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.1	0.1	0.3
Interest cost	0.2	0.3	0.5	0.5
Prior service cost	(0.5)	(0.5)	(1.6)	(1.4)
Recognized actuarial losses (gain)			(0.1)	0.1
Total	$ (0.3)	$ (0.1)	$ (1.1)	$ (0.5)