Defined Benefit Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended							6 Months Ended		12 Months Ended					6 Months Ended	12 Months Ended
	Dec. 31, 2012	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Equity Securities	Dec. 31, 2013 Fixed income	Dec. 31, 2013 Cash and cash equivalents	Dec. 31, 2013 Other Investment	Jun. 30, 2013 Pension Benefits	Dec. 31, 2011 Pension Benefits	Dec. 31, 2013 Pension Benefits	Dec. 31, 2012 Pension Benefits	Dec. 31, 2011 Pension Benefits	Dec. 31, 2013 Pension Benefits Minimum Age	Dec. 31, 2013 Pension Benefits Maximum Age	Jun. 30, 2013 Postretirement Benefits	Dec. 31, 2013 Postretirement Benefits	Dec. 31, 2012 Postretirement Benefits	Dec. 31, 2013 Postretirement Benefits Scenario, Forecast In the first quarter of 2014	Dec. 31, 2013 Postretirement Benefits Minimum Scenario, Forecast In the first quarter of 2014	Dec. 31, 2013 Postretirement Benefits Maximum Scenario, Forecast In the first quarter of 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plans, retirement benefits payment commencement age															55	65
Reduction in accrued retiree benefit plans	$ (29.8)	$ (34.7)			$ (5.3)								$ (0.4)					$ 34.7	$ 29.8	$ (14.7)
Recognition of actuarial (losses) gains			(5.2)	(42.2)	(80.0)							73.0	(66.0)				(4.0)	0.3	(9.9)	0.6
Defined benefit plans, reduction in liability										(20)
Defined benefit plans, curtailment charges											1.8									3.7
Defined benefit plans, amortization of net prior service costs												0.1						(19.4)		11.7
Period of prior service credit in net income																					2 years	3 years
Expected pension contributions in 2014			10
Defined benefit asset allocation, minimum						0.00%	25.00%
Defined benefit asset allocation, maximum						75.00%	100.00%	25.00%	20.00%
Defined benefit plans, blended long-term rate of return on plan assets			7.40%									7.80%	7.80%	8.50%
Defined Contribution Plan, cash contributions			$ 18.7	$ 16.1	$ 17.8