Host Inc. Earnings (Loss) Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
NET INCOME	$ 378	$ 105	$ 845	$ 478
Less: Net (income) loss attributable to non-controlling interests	(56)	(1)	(61)	(6)
NET INCOME ATTRIBUTABLE TO REPORTING ENTITY	$ 322	$ 104	$ 784	$ 472
Basic weighted average shares outstanding	739.9	738.8	739.6	738.5
Assuming distribution of common shares granted under the comprehensive stock plans, less shares assumed purchased at market	0.6	0.2	0.6	0.2
Diluted weighted average shares/units outstanding	740.5	739.0	740.2	738.7
Basic earnings per common share	$ 0.43	$ 0.14	$ 1.06	$ 0.64
Diluted earnings per common share	$ 0.43	$ 0.14	$ 1.06	$ 0.64