INCOME TAXES - Effective Income Tax Rate Applicable to Continuing Operations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
U.S. federal statutory income tax	$ 154	$ 90	$ 29
State income taxes, net of federal tax benefit	6	4	4
REIT income not subject to federal income tax	(94)	(80)	(37)
Foreign taxes	8	20	4
Federal income tax credits	0	(4)	(4)
Medicare Part D subsidy	0	0	26
Provision for unrecognized tax benefits	(6)	(7)	(3)
REIT conversion benefit	0	0	(1,064)
Cellulosic biofuel producer credit	0	0	(149)
Repatriation of Canadian earnings	0	(76)	0
State income tax settlement	(10)	0	0
Other, net	(3)	(9)	2
Total income tax provision (benefit)	$ 55	$ (62)	$ (1,192)
Effective income tax rate	12.50%	(23.30%)