Pension Plans, Other Postretirement Benefits, and Defined-Contribution Plans - Fair Value of Pension Plan Assets by Asset Category and Input Level Table (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Net receivables related to investments	$ 2		$ 4
Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(17)		(11)
Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,769	[1]	1,469	[1]
Fair Value, Inputs, Level 1 [Member] | Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(17)		(11)
Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	683	[1]	508	[1]
Fair Value, Inputs, Level 2 [Member] | Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	849	[1]	742	[1]
Fair Value, Inputs, Level 3 [Member] | Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	237	[1]	219	[1]	191
Cash and Cash Equivalents [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	97		59
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17		23
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	80		36
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Mortgage-backed Securities [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54		63
Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	54		63
Mortgage-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
U.S. Government Securities [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52		54
U.S. Government Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
U.S. Government Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	52		54
U.S. Government Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Other Fixed-Income Securities [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	239	[2]	236	[2]
Other Fixed-Income Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42	[2]	40	[2]
Other Fixed-Income Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	197	[2]	196	[2]
Other Fixed-Income Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]	0	[2]
Equity Securities Domestic [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	561		422
Equity Securities Domestic [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	445		313
Equity Securities Domestic [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	116		109
Equity Securities Domestic [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Equity Securities International [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	451		350
Equity Securities International [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	148		112
Equity Securities International [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	303		238
Equity Securities International [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Real Estate [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	133		124
Real Estate [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Real Estate [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	47		46
Real Estate [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	86		78		72
Private Equity [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	72		64
Private Equity [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Private Equity [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Private Equity [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	72		64		55
Hedge Funds and Other Alternative Strategies Asset Position [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	110		97
Hedge Funds and Other Alternative Strategies Asset Position [Member] | Fair Value, Inputs, Level 1 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31		20
Hedge Funds and Other Alternative Strategies Asset Position [Member] | Fair Value, Inputs, Level 2 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Hedge Funds and Other Alternative Strategies Asset Position [Member] | Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	79		77		64
Hedge Funds and Other Alternative Strategies Liability Position [Member] | Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(17)		(11)
Hedge Funds and Other Alternative Strategies Liability Position [Member] | Fair Value, Inputs, Level 1 [Member] | Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(17)		(11)
Hedge Funds and Other Alternative Strategies Liability Position [Member] | Fair Value, Inputs, Level 2 [Member] | Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Hedge Funds and Other Alternative Strategies Liability Position [Member] | Fair Value, Inputs, Level 3 [Member] | Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0		$ 0

[1] Amount excludes net receivables of $2 million for 2013 and $4 million for 2012, primarily related to Level 1 investments.

[2] Amounts include investments in diversified fixed-income collective investment funds with exposure to mortgage-backed securities, government-issued securities, corporate debt, and other fixed-income securities.