Reclassifications Out of Accumulated Other Comprehensive Income/(Loss) - Summary of Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	$ (2.1)	$ (4.9)
Reclassification Out of Accumulated Other Comprehensive Income/(Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications	0.8
Reclassification Out of Accumulated Other Comprehensive Income/(Loss) [Member] \| Defined Benefit Pension Plan Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service credit	(0.4)
Amortization of actuarial net losses	1.4
Total before tax	1.0
Income tax expense	(0.2)
Total reclassifications	$ 0.8

Reclassifications Out of Accumulated Other Comprehensive Income/(Loss) - Summary of Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) (USD $)
In Millions, unless otherwise specified

3 Months Ended

Mar. 31, 2014

Mar. 31, 2013

Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]

Income tax expense

$ (2.1)

$ (4.9)

Reclassification Out of Accumulated Other Comprehensive Income/(Loss) [Member]

Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]

Total reclassifications

0.8

Reclassification Out of Accumulated Other Comprehensive Income/(Loss) [Member] | Defined Benefit Pension Plan Items [Member]