Related Party Transactions - Schedule of Related Party Expenses Incurred and Portfolio Company Incentive Compensation Awards and Capitalized Transaction Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 26,495	$ 12,273	$ 75,863	$ 29,310
Affiliate Service Provider Incentive Compensation Awards	(31)	500	969	1,500
Capitalized Transaction Support Services	3,252	5,365	5,881	7,328
LivCor L.L.C. [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	7,150	4,937	19,474	13,363
Affiliate Service Provider Incentive Compensation Awards	(5)	77	149	231
Capitalized Transaction Support Services	772	1,203	2,533	2,124
Gateway Industrial Properties L.L.C. [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses				2,524
Affiliate Service Provider Incentive Compensation Awards				236
Capitalized Transaction Support Services				27
ShopCore Properties TRS Management L.L.C. [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	1,411	460	3,532	1,161
Affiliate Service Provider Incentive Compensation Awards	(1)	6	12	19
Capitalized Transaction Support Services	107	300	422	315
Link Industrial Properties L.L.C. [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	13,312	5,305	39,334	8,417
Affiliate Service Provider Incentive Compensation Awards	(16)	261	505	546
Capitalized Transaction Support Services	2,373	3,862	2,926	4,862
BRE Hotels And Resorts LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	4,012	1,223	11,661	2,964
Affiliate Service Provider Incentive Compensation Awards	(9)	156	303	468
Revantage Corporate Services, L.L.C. [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	440	$ 348	1,397	$ 881
Equity Office Management, L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 170		$ 465