Benefit Obligations (Schedule of Fair Values of Pension Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Assets, Fair Value Non-Financial Receivables	$ 38		$ 26
Pension Plan Assets, Fair Value Non-Financial Payables	64		72
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	2,588	[1]	2,506	[2]
Total liabilities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	74		149
Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	10		8
Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	1		1
Obligations under securities lending [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	63		140
Total assets [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	2,662		2,655
Cash and cash equivalents [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	14		9
Loans [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			26
Equities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	153		200
Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	10		8
Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			1
US companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	327		402
International companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	358		335
Collateralized mortgage obligations [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	6		21
Corporate debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	762		780
Treasuries, other debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	411		269
Mortgage backed securities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	44		68
Registered investment companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	282		293
Securities lending collateral [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	63		140
Short-term investments [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	186		58
Insurance contracts [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	29		29
Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	17		16
Fair Value, Inputs, Level 1 [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	743	[1]	788	[2]
Fair Value, Inputs, Level 1 [Member] | Total liabilities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	63		140
Fair Value, Inputs, Level 1 [Member] | Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Obligations under securities lending [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	63		140
Fair Value, Inputs, Level 1 [Member] | Total assets [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	806		928
Fair Value, Inputs, Level 1 [Member] | Cash and cash equivalents [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	14		9
Fair Value, Inputs, Level 1 [Member] | Loans [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			0
Fair Value, Inputs, Level 1 [Member] | Equities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			0
Fair Value, Inputs, Level 1 [Member] | US companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	327		402
Fair Value, Inputs, Level 1 [Member] | International companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	358		335
Fair Value, Inputs, Level 1 [Member] | Collateralized mortgage obligations [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Corporate debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	1		2
Fair Value, Inputs, Level 1 [Member] | Treasuries, other debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	36		33
Fair Value, Inputs, Level 1 [Member] | Mortgage backed securities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Registered investment companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Securities lending collateral [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	63		140
Fair Value, Inputs, Level 1 [Member] | Short-term investments [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Insurance contracts [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 1 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	7		7
Fair Value, Inputs, Level 2 [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	1,845	[1]	1,692	[2]
Fair Value, Inputs, Level 2 [Member] | Total liabilities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	11		9
Fair Value, Inputs, Level 2 [Member] | Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	10		8
Fair Value, Inputs, Level 2 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	1		1
Fair Value, Inputs, Level 2 [Member] | Obligations under securities lending [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 2 [Member] | Total assets [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	1,856		1,701
Fair Value, Inputs, Level 2 [Member] | Cash and cash equivalents [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 2 [Member] | Loans [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			0
Fair Value, Inputs, Level 2 [Member] | Equities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	153		200
Fair Value, Inputs, Level 2 [Member] | Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	10		8
Fair Value, Inputs, Level 2 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			1
Fair Value, Inputs, Level 2 [Member] | US companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 2 [Member] | International companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 2 [Member] | Collateralized mortgage obligations [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	6		21
Fair Value, Inputs, Level 2 [Member] | Corporate debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	761		778
Fair Value, Inputs, Level 2 [Member] | Treasuries, other debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	375		236
Fair Value, Inputs, Level 2 [Member] | Mortgage backed securities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	44		68
Fair Value, Inputs, Level 2 [Member] | Registered investment companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	282		293
Fair Value, Inputs, Level 2 [Member] | Securities lending collateral [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 2 [Member] | Short-term investments [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	186		58
Fair Value, Inputs, Level 2 [Member] | Insurance contracts [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	29		29
Fair Value, Inputs, Level 2 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	10		9
Fair Value, Inputs, Level 3 [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0	[1]	26	[2]
Fair Value, Inputs, Level 3 [Member] | Total liabilities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Obligations under securities lending [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Total assets [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		26
Fair Value, Inputs, Level 3 [Member] | Cash and cash equivalents [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Loans [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			26
Fair Value, Inputs, Level 3 [Member] | Equities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Swaps [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets			0
Fair Value, Inputs, Level 3 [Member] | US companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | International companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Collateralized mortgage obligations [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Corporate debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Treasuries, other debt [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Mortgage backed securities [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Registered investment companies [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Securities lending collateral [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Short-term investments [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Insurance contracts [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	0		0
Fair Value, Inputs, Level 3 [Member] | Other [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net assets	$ 0		$ 0

[1] Total net assets excludes non-financial plan receivables and payables of $38 million and $64 million, respectively. Non-financial items include due to/from broker, interest receivables and accrued expenses.

[2] Total net assets excludes non-financial plan receivables and payables of $26 million and $72 million, respectively. Non-financial items include due to/from broker, interest receivables and accrued expenses.