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
	Mar. 31, 2019	Mar. 31, 2018
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 7,438	$ 1,935
Affiliate Service Provider Incentive Compensation Awards	500
Capitalized Transaction Support Services	400	179
LivCor LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	4,028	1,143
Affiliate Service Provider Incentive Compensation Awards	141
Capitalized Transaction Support Services	358
Gateway Industrial Properties L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	2,095	405
Affiliate Service Provider Incentive Compensation Awards	236
Capitalized Transaction Support Services	27	179
ShopCore Properties TRS Management LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	402	240
Affiliate Service Provider Incentive Compensation Awards	5
Capitalized Transaction Support Services	15
BRE Hotels And Resorts LLC [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	654	$ 147
Affiliate Service Provider Incentive Compensation Awards	118
Revantage Corporate Services, L.L.C [Member]
Related Party Transaction [Line Items]
Affiliate Service Provider Expenses	$ 259