Related Party Transactions - Schedule of Expenses Incurred and Capitalized Transaction Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 4,130	$ 790	$ 9,215	$ 1,416
Capitalized Transaction Support Fees	350	620	350	620
LivCor LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	1,995	394	5,186	464
Capitalized Transaction Support Fees	145	600	145	600
Gateway Industrial Properties L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	1,336		2,414
Capitalized Transaction Support Fees	196		196
ShopCore Properties TRS Management LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	470	72	968	142
BRE Hotels And Resorts LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	260	38	578	53
Equity Office Management, L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses		286		757
Capitalized Transaction Support Fees		$ 20		$ 20
Revantage Corporate Services, L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	69		69
Capitalized Transaction Support Fees	$ 9		$ 9