PARENT COMPANY CONDENSED FINANCIAL INFORMATION, Condensed Statements of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Statements of Cash Flows [Abstract]
Cash Flows from Operations (including dividends received from subsidiaries)	$ 86	$ 150	$ 115
Cash Flows from Investing Activities:
Capital expenditures	(67)	(95)	(31)
Purchase of investments	(28)	(102)	(48)
Net cash used in investing activities	(71)	(150)	(31)
Cash Flows from Financing Activities:
Proceeds from issuance of capital stock and other	10	7	(1)
Dividends paid	(53)	(52)	(52)
Net cash used in financing activities	(7)	(2)	(87)
Net increase (decrease) for the year	8	(2)	(3)
Balance, beginning of year	14	16	19
Balance, end of year	22	14	16
Other Cash Flow Information:
Income taxes paid, net of refunds	(25)	(46)	(38)
Other Non-cash Information:
Tax-deferred property sales	45	120	109
Tax-deferred property purchases	(39)	(148)	(95)
A&B (Parent Company) [Member]
Condensed Statements of Cash Flows [Abstract]
Cash Flows from Operations (including dividends received from subsidiaries)	96	37	90
Cash Flows from Investing Activities:
Capital expenditures	(10)	(14)	(6)
Purchase of investments	(58)	(67)	(96)
Proceeds from disposal of property and sale of investments	12	36	28
Net cash used in investing activities	(55)	(45)	(74)
Cash Flows from Financing Activities:
Change in intercompany payables/receivables	0	0	(13)
Proceeds from (repayments of) long-term debt, net	3	52	51
Proceeds from issuance of capital stock and other	10	7	(1)
Repurchases of capital stock	0	0	0
Dividends paid	(53)	(52)	(52)
Net cash used in financing activities	(40)	7	(15)
Net increase (decrease) for the year	(1)	(1)	1
Balance, beginning of year	0	1	0
Balance, end of year	1	0	1
Other Cash Flow Information:
Interest paid	(16)	(15)	(13)
Income taxes paid, net of refunds	(25)	(46)	(38)
Other Non-cash Information:
Depreciation expense	16	16	17
Tax-deferred property sales	16	65	29
Tax-deferred property purchases	$ (12)	$ (78)	$ (40)