Retirement Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Gain on curtailment		$ 3.7	$ 38.7
Defined benefit plan, accumulated benefit obligation	3,937.0	4,343.9
Pension and postretirement contributions	29.6	148.7	54.6
Threshold for recognition in net periodic benefit costs, percentage of projected benefit obligation or fair value of plan assets	10.00%
Employer matching contributions rate		40.00%
Maximum participant contributions as a percentage of eligible compensation per pay period		6.00%
Recognized expense		30.8
Multi-employer plan, period contributions	1.3	1.3	1.7
Percentage of employer contribution, maximum	5.00%	5.00%	5.00%
Reduction in pension liability due to curtailment	30.1
Red zone status, percentage	65.00%
Other Charges	38.4
Multi-employer pension plan withdrawal obligations
Defined Benefit Plan Disclosure [Line Items]
Other Charges	38.4		15.1
Multi-employer pension plan withdrawal obligations | Complete And Partial Withdrawal From Multi Employer Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Other Charges	53.1
Multi-employer pension plan withdrawal obligations | Facility closures
Defined Benefit Plan Disclosure [Line Items]
Other Charges	14.7
Equity Securities and Other Investments
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage	75.00%
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentage	25.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Potential withdrawal obligations	15
Maximum
Defined Benefit Plan Disclosure [Line Items]
Potential withdrawal obligations	25
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Gain on curtailment		3.7	38.7
Pension and postretirement contributions	21.6	140.7
Medicare reimbursements
Reduction in pension liability due to curtailment	0.1	(2.6)
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Gain on curtailment
Pension and postretirement contributions	8.0	8.0
Medicare reimbursements	2.7	3.3
Reduction in pension liability due to curtailment	30.6	(0.5)
Other Postretirement Benefit Plans, Defined Benefit | Medicare Part D Subsidies
Defined Benefit Plan Disclosure [Line Items]
Medicare reimbursements	0.5	3.3
Pension Plans Defined benefit | Minimum
Defined Benefit Plan Disclosure [Line Items]
Pension and other postretirement expected contributions for next year	59
Pension and other postretirement expected contributions for 2015	24
Pension Plans Defined benefit | Maximum
Defined Benefit Plan Disclosure [Line Items]
Pension and other postretirement expected contributions for next year	79
Pension and other postretirement expected contributions for 2015	29
EGWP
Defined Benefit Plan Disclosure [Line Items]
Medicare reimbursements	$ 2.7