Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Significant Accounting Policies [Line Items]
Right-of-use assets	$ 616
Lease liabilities	625
ASU 2016-02
Significant Accounting Policies [Line Items]
Lease liabilities	628
ASU 2016-02 | Asset
Significant Accounting Policies [Line Items]
Right-of-use assets	619
ASU 2016-02 | Rent Liability
Significant Accounting Policies [Line Items]
Reduction of the rent liability due to adoption	$ 9
Host L.P.
Significant Accounting Policies [Line Items]
Percentage of the common OP units	99.00%