Fair Value Measurements - Summary of Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring basis - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	$ 6,949	$ 0
Quoted Prices in Active Markets for Identical Assets Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	0	0
Significant Other Observable Inputs Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	0	0
Significant Unobservable Inputs Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loan participations held-for-investment	$ 6,949	$ 0