FAIR VALUE MEASUREMENTS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 609			$ 609			$ 594
Gross unrealized gains	380			380			317
Gross unrealized losses	(8)			(8)			(3)
Estimated fair value	981			981			908
Proceeds from sales	181		204	507		524
Gross realized gains	2		3	13		12
Gross realized losses	8		1	15		6
Total Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	367			367			325
Gross unrealized gains	10			10			25
Gross unrealized losses	(6)			(6)			(1)
Estimated fair value	371			371			349
Debt Securities Issued By The U.S. Treasury And Other U.S. Government Corporations And Agencies
Schedule of Available-for-sale Securities [Line Items]
Cost	130	[1]		130	[1]		147
Gross unrealized gains	4	[1]		4	[1]		9
Gross unrealized losses	(1)	[1]		(1)	[1]		0
Estimated fair value	133	[1]		133	[1]		156
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Cost	102	[2]		102	[2]		57
Gross unrealized gains	3	[2]		3	[2]		6
Gross unrealized losses	(1)	[2]		(1)	[2]		0
Estimated fair value	104	[2]		104	[2]		63
Other Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	135	[3]		135	[3]		121
Gross unrealized gains	3	[3]		3	[3]		10
Gross unrealized losses	(4)	[3]		(4)	[3]		(1)
Estimated fair value	134	[3]		134	[3]		130
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Cost	231			231			249
Gross unrealized gains	370			370			292
Gross unrealized losses	(2)			(2)			(2)
Estimated fair value	599			599			539
Cash And Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Cost	11			11			20
Gross unrealized gains	0			0			0
Gross unrealized losses	0			0			0
Estimated fair value	$ 11			$ 11			$ 20

[1] Maturity dates are 2014-2056.

[2] Maturity dates are 2014-2062.

[3] Maturity dates are 2013-2111.