Pension and Other Postretirement Benefits - Additional Information (Detail) (United Steelworkers Labor Agreement [Member], USD $) In Millions, unless otherwise specified	0 Months Ended		3 Months Ended	6 Months Ended
	Jun. 06, 2014	May 31, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 06, 2014 Employees Location	May 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Term of labor agreement, in years	5 years
Number of employees covered by labor agreement					6,100
Number of locations affected by labor agreement					10
Pretax costs related to preparation for and ratification of new agreement			$ 17	$ 18
Labor agreement expired, date				May 15, 2014
After-tax costs related to preparation for and ratification of new agreement			11	12
Discount rate used to determine pension benefit obligation						4.25%	4.80%
Increase in pension liability, plan amendment		100
Accumulated increase in net actuarial loss after-tax, plan amendment				65
Annual decrease in net periodic benefit cost, plan amendment			2	13
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual decrease in net periodic benefit cost, plan amendment				$ 11