Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Condensed Consolidated Statements of Cash Flows (Unaudited) [Abstract]
Cash Flows from Operating Activities	$ 17	$ 39
Cash Flows from Investing Activities:
Capital expenditures	(35)	(24)
Proceeds from disposal of property and other assets	10	9
Deposits into Capital Construction Fund	(2)	(2)
Withdrawals from Capital Construction Fund	2	2
Increase in investments	(15)	(48)
Reduction in investments	8	12
Net cash used in investing activities	(32)	(51)
Cash Flows from Financing Activities:
Proceeds from issuances of debt	178	108
Payments of debt and deferred financing costs	(147)	(50)
Proceeds from (payments on) line-of-credit agreements, net	3	(3)
Proceeds from issuances of capital stock and other	9	3
Dividends paid	(27)	(26)
Net cash provided by financing activities	16	32
Net Increase in Cash and Cash Equivalents	1	20
Other Cash Flow Information:
Interest paid	(15)	(13)
Income taxes paid	(14)	(21)
Other Non-cash Information:
Depreciation and amortization expense	53	52
Tax-deferred property sales	36	76
Tax-deferred property purchases	(11)	(53)
Common stock dividends declared but not yet paid	$ 13	$ 13