Pensions and Other Employee Benefits - Fair Value of Company's Pension Plans' and Postretirement Benefit Plans' Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Postretirement Benefit Plans Assets [Member]
Equity securities(1):
Fair value of company's plan assets	$ 47	$ 42
Postretirement Benefit Plans Assets [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	41	37
Postretirement Benefit Plans Assets [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	6	5
Postretirement Benefit Plans Assets [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | U.S. Equity [Member]
Equity securities(1):
Fair value of company's plan assets	27	24
Postretirement Benefit Plans Assets [Member] | U.S. Equity [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	27	24
Postretirement Benefit Plans Assets [Member] | U.S. Equity [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | U.S. Equity [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | International equity [Member]
Equity securities(1):
Fair value of company's plan assets	2	2
Postretirement Benefit Plans Assets [Member] | International equity [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	1	1
Postretirement Benefit Plans Assets [Member] | International equity [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	1	1
Postretirement Benefit Plans Assets [Member] | International equity [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | Fixed Income - Investment Grade [Member]
Equity securities(1):
Fair value of company's plan assets	14	13
Postretirement Benefit Plans Assets [Member] | Fixed Income - Investment Grade [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	11	11
Postretirement Benefit Plans Assets [Member] | Fixed Income - Investment Grade [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	3	2
Postretirement Benefit Plans Assets [Member] | Fixed Income - Investment Grade [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | Fixed Income - High Yield [Member]
Equity securities(1):
Fair value of company's plan assets	1	1
Postretirement Benefit Plans Assets [Member] | Fixed Income - High Yield [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | Fixed Income - High Yield [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	1	1
Postretirement Benefit Plans Assets [Member] | Fixed Income - High Yield [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | Real Estate Investment Trusts [Member]
Equity securities(1):
Fair value of company's plan assets	2	1
Postretirement Benefit Plans Assets [Member] | Real Estate Investment Trusts [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	2	1
Postretirement Benefit Plans Assets [Member] | Real Estate Investment Trusts [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | Real Estate Investment Trusts [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | Other [Member]
Equity securities(1):
Fair value of company's plan assets	1	1
Postretirement Benefit Plans Assets [Member] | Other [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets
Postretirement Benefit Plans Assets [Member] | Other [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	1	1
Postretirement Benefit Plans Assets [Member] | Other [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member]
Equity securities(1):
Fair value of company's plan assets	1,753	1,460
U.S. based Pension Plans [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	1,292	1,065
U.S. based Pension Plans [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	461	395
U.S. based Pension Plans [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | U.S. Equity [Member]
Equity securities(1):
Fair value of company's plan assets	893	712
U.S. based Pension Plans [Member] | U.S. Equity [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	893	712
U.S. based Pension Plans [Member] | U.S. Equity [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | U.S. Equity [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | International equity [Member]
Equity securities(1):
Fair value of company's plan assets	184	165
U.S. based Pension Plans [Member] | International equity [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	67	65
U.S. based Pension Plans [Member] | International equity [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	117	100
U.S. based Pension Plans [Member] | International equity [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | Fixed Income - Investment Grade [Member]
Equity securities(1):
Fair value of company's plan assets	391	374
U.S. based Pension Plans [Member] | Fixed Income - Investment Grade [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	194	188
U.S. based Pension Plans [Member] | Fixed Income - Investment Grade [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	197	186
U.S. based Pension Plans [Member] | Fixed Income - Investment Grade [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | Fixed Income - High Yield [Member]
Equity securities(1):
Fair value of company's plan assets	105	86
U.S. based Pension Plans [Member] | Fixed Income - High Yield [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | Fixed Income - High Yield [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	105	86
U.S. based Pension Plans [Member] | Fixed Income - High Yield [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | Real Estate Investment Trusts [Member]
Equity securities(1):
Fair value of company's plan assets	138	100
U.S. based Pension Plans [Member] | Real Estate Investment Trusts [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	138	100
U.S. based Pension Plans [Member] | Real Estate Investment Trusts [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | Real Estate Investment Trusts [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | Other [Member]
Equity securities(1):
Fair value of company's plan assets	42	23
U.S. based Pension Plans [Member] | Other [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets
U.S. based Pension Plans [Member] | Other [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	42	23
U.S. based Pension Plans [Member] | Other [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member]
Equity securities(1):
Fair value of company's plan assets	273	252
Canadian based Pension Plans [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	144	124
Canadian based Pension Plans [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	129	128
Canadian based Pension Plans [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | U.S. Equity [Member]
Equity securities(1):
Fair value of company's plan assets	56	40
Canadian based Pension Plans [Member] | U.S. Equity [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	43	29
Canadian based Pension Plans [Member] | U.S. Equity [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	13	11
Canadian based Pension Plans [Member] | U.S. Equity [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | International equity [Member]
Equity securities(1):
Fair value of company's plan assets	119	109
Canadian based Pension Plans [Member] | International equity [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	98	90
Canadian based Pension Plans [Member] | International equity [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	21	19
Canadian based Pension Plans [Member] | International equity [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Fixed Income - Investment Grade [Member]
Equity securities(1):
Fair value of company's plan assets	88	93
Canadian based Pension Plans [Member] | Fixed Income - Investment Grade [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Fixed Income - Investment Grade [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	88	93
Canadian based Pension Plans [Member] | Fixed Income - Investment Grade [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Fixed Income - High Yield [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Fixed Income - High Yield [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Fixed Income - High Yield [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Fixed Income - High Yield [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Real Estate Investment Trusts [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Real Estate Investment Trusts [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Real Estate Investment Trusts [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Real Estate Investment Trusts [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets
Canadian based Pension Plans [Member] | Other [Member]
Equity securities(1):
Fair value of company's plan assets	10	10
Canadian based Pension Plans [Member] | Other [Member] | Level 1 [Member]
Equity securities(1):
Fair value of company's plan assets	3	5
Canadian based Pension Plans [Member] | Other [Member] | Level 2 [Member]
Equity securities(1):
Fair value of company's plan assets	7	5
Canadian based Pension Plans [Member] | Other [Member] | Level 3 [Member]
Equity securities(1):
Fair value of company's plan assets