Employee Benefits (Details 2) (Pension Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair values of pension plan assets by asset category
Assets at fair value	$ 918	$ 914	$ 839
Mutual Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	11
Mutual Funds [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	150	133
Mutual Funds [Member] | Fixed income - U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	4
Mutual Funds [Member] | Fixed income - International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	2
Common Trust Funds [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	24	24
Common Trust Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	21	27
Common Trust Funds [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	4	11
Common Trust Funds [Member] | Short-term investments [Member]
Fair values of pension plan assets by asset category
Assets at fair value	40	43
Common Trust Funds [Member] | Convertible securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	44	45
Insurance Company Contracts [Member]
Fair values of pension plan assets by asset category
Assets at fair value	12	11
Multi Strategy Investment Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	4	6
Government Bonds International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	3	2
Convertible bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	1	2
Equity Securities [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	1	1
Equity Securities [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	336	376
Equity Securities [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	39	2
Corporate bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	70	58
Corporate bonds - International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	7	5
Government and agency bonds U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	73	75
Government and agency bonds U.S. [Member] | Mutual Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	72	53
Level 1 [Member]
Fair values of pension plan assets by asset category
Assets at fair value	614	605
Level 1 [Member] | Mutual Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	11
Level 1 [Member] | Mutual Funds [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	149	133
Level 1 [Member] | Mutual Funds [Member] | Fixed income - U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	4
Level 1 [Member] | Mutual Funds [Member] | Fixed income - International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	2
Level 1 [Member] | Common Trust Funds [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Common Trust Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Common Trust Funds [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Common Trust Funds [Member] | Short-term investments [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Common Trust Funds [Member] | Convertible securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Insurance Company Contracts [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Multi Strategy Investment Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Government Bonds International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Convertible bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	1	1
Level 1 [Member] | Equity Securities [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	336	376
Level 1 [Member] | Equity Securities [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	39	42
Level 1 [Member] | Corporate bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Corporate bonds - International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Government and agency bonds U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 1 [Member] | Government and agency bonds U.S. [Member] | Mutual Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	72	53
Level 2 [Member]
Fair values of pension plan assets by asset category
Assets at fair value	288	292
Level 2 [Member] | Mutual Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0
Level 2 [Member] | Mutual Funds [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	1	0
Level 2 [Member] | Common Trust Funds [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	24	24
Level 2 [Member] | Common Trust Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	21	27
Level 2 [Member] | Common Trust Funds [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	4	11
Level 2 [Member] | Common Trust Funds [Member] | Short-term investments [Member]
Fair values of pension plan assets by asset category
Assets at fair value	40	43
Level 2 [Member] | Common Trust Funds [Member] | Convertible securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	44	45
Level 2 [Member] | Insurance Company Contracts [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 2 [Member] | Multi Strategy Investment Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 2 [Member] | Government Bonds International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	3	2
Level 2 [Member] | Convertible bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	1	2
Level 2 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 2 [Member] | Equity Securities [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 2 [Member] | Equity Securities [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 2 [Member] | Corporate bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	70	58
Level 2 [Member] | Corporate bonds - International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	7	5
Level 2 [Member] | Government and agency bonds U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	73	75
Level 2 [Member] | Government and agency bonds U.S. [Member] | Mutual Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member]
Fair values of pension plan assets by asset category
Assets at fair value	16	17	37
Level 3 [Member] | Mutual Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0
Level 3 [Member] | Mutual Funds [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Common Trust Funds [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0
Level 3 [Member] | Common Trust Funds [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Common Trust Funds [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Common Trust Funds [Member] | Short-term investments [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Common Trust Funds [Member] | Convertible securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Insurance Company Contracts [Member]
Fair values of pension plan assets by asset category
Assets at fair value	12	11	11
Level 3 [Member] | Multi Strategy Investment Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	4	6	26
Level 3 [Member] | Government Bonds International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Convertible bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Equity Securities [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Equity Securities [Member] | U.S. [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Equity Securities [Member] | International [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Equity Securities [Member] | Common Trust Funds [Member] | Emerging Markets [Member]
Fair values of pension plan assets by asset category
Assets at fair value		0
Level 3 [Member] | Corporate bonds - U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Corporate bonds - International [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Government and agency bonds U.S. [Member] | Fixed income securities [Member]
Fair values of pension plan assets by asset category
Assets at fair value	0	0
Level 3 [Member] | Government and agency bonds U.S. [Member] | Mutual Funds [Member]
Fair values of pension plan assets by asset category
Assets at fair value	$ 0	$ 0