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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 12,273	$ 4,130	$ 29,310	$ 9,215
Affiliate Service Provider Incentive Compensation Awards	500		1,500
Capitalized Transaction Support Services	5,365	45	7,328	350
LivCor L.L.C. [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	4,937	1,995	13,363	5,186
Affiliate Service Provider Incentive Compensation Awards	77		231
Capitalized Transaction Support Services	1,203	44	2,124	145
Gateway Industrial Properties L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses		1,336	2,524	2,414
Affiliate Service Provider Incentive Compensation Awards			236
Capitalized Transaction Support Services			27	196
ShopCore Properties TRS Management LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	460	470	1,161	968
Affiliate Service Provider Incentive Compensation Awards	6		19
Capitalized Transaction Support Services	300		315
Link Industrial Properties LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	5,305		8,417
Affiliate Service Provider Incentive Compensation Awards	261		546
Capitalized Transaction Support Services	3,862		4,862
BRE Hotels And Resorts LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	1,223	260	2,964	578
Affiliate Service Provider Incentive Compensation Awards	156		468
Revantage Corporate Services, L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 348	69	$ 881	69
Capitalized Transaction Support Services		$ 1		$ 9