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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 9,599	$ 3,150	$ 17,037	$ 5,085
Affiliate Service Provider Incentive Compensation Awards	500		1,000
Capitalized Transaction Support Services	1,563	126	1,963	305
LivCor L.L.C. [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	4,398	2,048	8,426	3,191
Affiliate Service Provider Incentive Compensation Awards	13		154
Capitalized Transaction Support Services	563	101	921	101
Gateway Industrial Properties L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	429	673	2,524	1,078
Affiliate Service Provider Incentive Compensation Awards			236
Capitalized Transaction Support Services		17	27	196
ShopCore Properties TRS Management LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	299	258	701	498
Affiliate Service Provider Incentive Compensation Awards	8		13
Capitalized Transaction Support Services			15
Link Industrial Properties LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	3,112		3,112
Affiliate Service Provider Incentive Compensation Awards	285		285
Capitalized Transaction Support Services	1,000		1,000
BRE Hotels And Resorts LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	1,087	171	1,741	318
Affiliate Service Provider Incentive Compensation Awards	194		312
Revantage Corporate Services, L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 274		$ 533
Capitalized Transaction Support Services		$ 8		$ 8