Secured Debt Agreements, Net - Summary of Key Terms of Credit Facilities (Parenthetical) (Detail) - Credit Facilities [Member]	12 Months Ended
	Dec. 31, 2018 ExtensionOptions
Bank of America - Multi. JV [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes two one-year extension options which may be exercised at our sole discretion.
Number of extension options	2
Term of maturity date	1 year
Goldman Sachs - Multi. JV [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes a one-year extension option which may be exercised at our sole discretion.
Term of maturity date	1 year
Deutsche Bank [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes two one-year extension options which may be exercised at our sole discretion.
Number of extension options	2
Term of maturity date	1 year
Barclays [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes four one-year extension options which may be exercised at our sole discretion.
Number of extension options	4
Term of maturity date	1 year
MetLife [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes four one-year extension options which may be exercised at our sole discretion.
Number of extension options	4
Term of maturity date	1 year
Bank of America [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes two one-year extension options which may be exercised at our sole discretion.
Number of extension options	2
Term of maturity date	1 year
Goldman Sachs [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes three one-year extension options which may be exercised at our sole discretion.
Number of extension options	3
Term of maturity date	1 year