Related Party Transactions (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction
Management fee – related party	$ 9,027,000	$ 9,061,000	$ 17,828,000	$ 18,573,000
Investment in money market or mutual funds managed by affiliates of a related party	64,069,000	144,084,000	$ 64,069,000	144,084,000	$ 161,788,000	$ 53,199,000
Manager
Related Party Transaction
Management fee			1.50%
Amounts of transaction with related party	1,200,000	1,400,000	$ 2,800,000	3,200,000
Termination fee multiplier			3
Termination fees assessment period			24 months
Invesco Advisers, Inc. | Affiliated Entity
Related Party Transaction
Management fee – related party	202,000	182,000	$ 387,000	341,000
Investment in money market or mutual funds managed by affiliates of a related party	24,300,000		24,300,000		$ 149,900,000
Loans origination and commitment fees paid	$ 0	$ 189,000	$ 0	$ 692,000