Pensions and Other Postretirement Benefits (Net Periodic Benefit Costs) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2013 Pensions	Dec. 31, 2012 Pensions	Dec. 31, 2013 Pensions Defined Contribution Pension	Dec. 31, 2012 Pensions Defined Contribution Pension	Dec. 31, 2011 Pensions Defined Contribution Pension	Dec. 31, 2013 Pensions Other Postretirement Benefits	Dec. 31, 2012 Pensions Other Postretirement Benefits	Dec. 31, 2011 Pensions Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 57	$ 54	$ 57	$ 54	$ 57	$ 20	$ 19	$ 16
Interest cost		218	217	218	217	231	49	50	55
Expected return on plan assets				(286)	(261)	(280)
Amortization of prior service cost (credit)		2		(2)		1	(9)	(10)	(10)
Amortization of actuarial losses		80		102	133	106	28	31	26
Curtailments and special termination benefits	33	18	6	18		5
Net periodic benefit cost				$ 107	$ 143	$ 120	$ 88	$ 90	$ 87