Employee Benefit Plans - Components of Net Periodic Benefit Cost (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2.5	$ 3.2	$ 5.1	$ 6.5
Interest cost	5.7	5.3	11.4	10.8
Expected return on plan assets	(5.4)	(4.9)	(10.8)	(10.0)
Amortization of prior service cost	0.2	0.4	0.4	0.8
Amortization of net transition obligations		0.1		0.2
Recognized actuarial losses	2.6	3.1	5.2	6.2
Total	5.6	7.2	11.3	14.5
OPEB
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.1	0.1	0.1	0.2
Interest cost	0.1	0.1	0.2	0.2
Amortization of prior service cost	(0.3)	(0.1)	(0.5)	(0.3)
Recognized actuarial losses		0.1	0.1	0.2
Total	$ (0.1)	$ 0.2	$ (0.1)	$ 0.3