INCOME TAXES - Effective Income Tax Rate Applicable to Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
U.S. federal statutory income tax	$ 176	$ 354	$ 112
State income taxes, net of federal tax benefit	1	14	7
REIT income not subject to federal income tax	(158)	(161)	(101)
REIT benefit from change to tax law	(13)	0	0
Foreign taxes	0	(2)	(8)
Provision for unrecognized tax benefits	(7)	(4)	(193)
Repatriation of Canadian earnings	0	0	21
Domestic production activities deduction	0	0	(13)
Other, net	(2)	(16)	4
Total income tax provision (benefit)	$ (3)	$ 185	$ (171)
Effective income tax rate	(0.50%)	18.30%	(53.40%)