Investments In Marketable Securities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Debt securities:
Unsecured debentures	$ 377		$ 377		$ 665
Certificates of deposit	389		389		576
Government debt securities	26		26		31
Other	14		14		0
Subtotal	806		806		1,272
Equity securities:
Mutual funds	57		57		67
Common stock	1		1		1
Subtotal	58		58		68
Total available-for-sale	864		864		1,340
Equity securities:
Mutual funds	12		12		12
Total trading	12		12		12
TOTAL	876		876		1,352
Held-to-maturity Securities	7		7		4
Total marketable securities	883		883		1,356
Footnotes to Marketable Securities Detail Table [Abstract]
Amortized cost of commmon stock available-for-sale	1		1		4
Gain Loss On Marketable Securities
Gains included in earnings that relate to trading securities held at the reporting date	0	0	0	1
Unrealized gains (losses) on available-for-sale securities included in other comprehensive income	0	(1)	0	(3)
Proceeds from sales of available-for-sale securities	2,080	1,846	3,603	3,077
Gross realized gains on sales	1	3	1	4
Level 1
Debt securities:
Unsecured debentures	0		0		0
Certificates of deposit	0		0		0
Government debt securities	0		0		0
Other	0		0		0
Subtotal	0		0		0
Equity securities:
Mutual funds	0		0		0
Common stock	1		1		1
Subtotal	1		1		1
Total available-for-sale	1		1		1
Equity securities:
Mutual funds	12		12		12
Total trading	12		12		12
TOTAL	13		13		13
Level 2
Debt securities:
Unsecured debentures	377		377		665
Certificates of deposit	389		389		576
Government debt securities	26		26		31
Other	14		14		0
Subtotal	806		806		1,272
Equity securities:
Mutual funds	57		57		67
Common stock	0		0		0
Subtotal	57		57		67
Total available-for-sale	863		863		1,339
Equity securities:
Mutual funds	0		0		0
Total trading	0		0		0
TOTAL	863		863		1,339
Level 3
Debt securities:
Unsecured debentures	0		0		0
Certificates of deposit	0		0		0
Government debt securities	0		0		0
Other	0		0		0
Subtotal	0		0		0
Equity securities:
Mutual funds	0		0		0
Common stock	0		0		0
Subtotal	0		0		0
Total available-for-sale	0		0		0
Equity securities:
Mutual funds	0		0		0
Total trading	0		0		0
TOTAL	$ 0		$ 0		$ 0