Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements of Cash Flows (Unaudited) [Abstract]
Cash Flows from Operating Activities	$ 42	$ 81
Cash Flows from Investing Activities:
Capital expenditures	(51)	(39)
Proceeds from disposal of property and other assets	10	28
Deposits into Capital Construction Fund	(4)	(4)
Withdrawals from Capital Construction Fund	4	4
Increase in investments	(23)	(78)
Reduction in investments	8	12
Net cash used in investing activities	(56)	(77)
Cash Flows from Financing Activities:
Proceeds from issuances debt	169	163
Payments of debt and deferred financing costs	(111)	(111)
Proceeds from (payments on) line-of-credit agreements, net	(10)	(23)
Proceeds from issuances of capital stock and other	9	4
Dividends paid	(40)	(39)
Net cash provided by (used in) financing activities	17	(6)
Net Increase (Decrease) in Cash and Cash Equivalents	3	(2)
Other Cash Flow Information:
Interest paid	(20)	(21)
Income taxes paid	(15)	(40)
Other Non-cash Information:
Depreciation and amortization expense	81	79
Tax-deferred real estate sales	44	78
Tax-deferred real estate purchases	$ (31)	$ (91)