Other Expenses - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Management fee - percent of outstanding equity balance	1.50%
Incentive fee computation-percent of the product per agreement	20.00%
Incentive fee computation-percent of outstanding Equity per annum	7.00%
Management fees description	Manager is entitled to an incentive fee in an amount equal to the product of (i) 20% and (ii) the excess of (a) our Core Earnings (as defined in our Management Agreement) for the previous 12-month period over (b) an amount equal to 7.00% per annum multiplied by our outstanding Equity, provided that our Core Earnings over the prior three-year period is greater than zero. Core Earnings, as defined in our Management Agreement, is generally equal to our net income (loss) prepared in accordance with GAAP, excluding (i) certain non-cash items, (ii) the net income (loss) related to our legacy portfolio, and (iii) incentive management fees.
Management fees	$ 78,435	$ 74,834	$ 54,841
Manager [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Management fees	55,300	47,000	38,600
Total incentive compensation payments	23,200	27,900	$ 16,200
Accrued management and incentive fees payable	$ 20,200	$ 18,600