INCOME TAXES - Effective Income Tax Rate Applicable to Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
U.S. federal statutory income tax	$ 250	$ 177	$ 123
State income taxes, net of federal tax benefit	(2)	(3)	(5)
REIT income not subject to federal income tax	(198)	(99)	(158)
REIT benefit from change to tax law	0	0	(13)
Tax affect of U.S. corporate rate change	74	0	0
Foreign taxes	54	(4)	4
Provision for unrecognized tax benefits	(2)	0	(7)
Repatriation of Canadian earnings	(22)	24	0
Other, net	(20)	(6)	(2)
Total income tax provision (benefit)	$ 134	$ 89	$ (58)
Effective income tax rate	18.80%	17.60%	(16.40%)