Defined Benefit Pension And Other Postretirement Plans (Estimated Future Benefit Payments) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2014	$ 186
2015	181
2016	177
2017	178
2018	175
2019 through 2023	814
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2014	26	[1]
2015	29	[1]
2016	32	[1]
2017	34	[1]
2018	38	[1]
2019 through 2023	$ 231	[1]

[1] Effective 2013, as a result of the Patient Protection and Affordable Care Act, future Medicare reimbursements will no longer be tax deductible and must be used to reduce the costs of providing Medicare part D equivalent prescription drug benefits to retirees.