Schedule I - Condensed Financial Information Of Parent (Balance Sheet) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
ASSETS
Cash and equivalents	$ 255	$ 545	$ 622	$ 92
Accounts and notes receivable affiliates	473	517
Other current assets	132	109
Total current assets	2,295	2,890
Other	845	750
TOTAL ASSETS	23,645	23,511	23,702
LIABILITIES AND EQUITY
Short-term debt	148	269
Other current liabilities	207	283
Total current liabilities	1,785	1,888
Credit facility borrowings		460
Long-term debt	6,677	6,853
Other deferred credits and other noncurrent liabilities	447	615
Commitments and Contingencies
Retained earnings	2,369	2,225
Stockholders' equity	8,068	7,884	8,060
TOTAL LIABILITIES AND EQUITY	23,645	23,511
Parent Company [Member]
ASSETS
Cash and equivalents	3	4	24	22
Advances to money pool	340	64
Accounts and notes receivable affiliates	57	405
Other current assets		2
Total current assets	400	475
Investments in subsidiaries	7,532	7,681
Intercompany note receivable	425	425
Other	333	403
TOTAL ASSETS	8,690	8,984
LIABILITIES AND EQUITY
Short-term debt	148	269
Accounts payable affiliates	13	41
Other current liabilities	62	75
Total current liabilities	223	385
Credit facility borrowings		360
Long-term debt	424	423
Other deferred credits and other noncurrent liabilities	74	69
Total liabilities	721	1,237
Commitments and Contingencies
Common stock, $.01 par value, 400.0 shares authorized shares outstanding of 242.6 and 240.4, respectively	2	2
Other paid-in capital	5,598	5,520
Retained earnings	2,369	2,225
Stockholders' equity	7,969	7,747
TOTAL LIABILITIES AND EQUITY	$ 8,690	$ 8,984