Investments - Schedule of Company's Investments in Limited Partnerships (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Investment Securities [Line Items]
Carrying Value	$ 26,695	$ 28,133
Unfunded Balance	6,465	11,073
Private US Lower Middle Market Companies [Member]
Investment Securities [Line Items]
Carrying Value	4,613	6,076
Unfunded Balance	$ 0	$ 2,085
Percentage investment held by the entity	15.37%	15.37%
Bank Loans Public and Private Corporate Bonds Asset Backed Securities Equity and Debt Restructuring [Member]
Investment Securities [Line Items]
Carrying Value	$ 3,347	$ 3,423
Unfunded Balance	$ 0	$ 0
Percentage investment held by the entity	1.67%	1.69%
Power Utility and Energy Industries and Infrastructure [Member]
Investment Securities [Line Items]
Carrying Value	$ 5,723	$ 6,270
Unfunded Balance	$ 0	$ 1,401
Percentage investment held by the entity	0.18%	0.18%
Senior and Junior Debts of Private Equity-Backed Companies [Member]
Investment Securities [Line Items]
Carrying Value	$ 3,940	$ 4,437
Unfunded Balance	$ 0	$ 0
Percentage investment held by the entity	0.56%	0.57%
Mature Real Estate Private Equity Funds And Portfolios Globally [Member]
Investment Securities [Line Items]
Carrying Value	$ 6,417	$ 5,977
Unfunded Balance	$ 3,881	$ 4,537
Percentage investment held by the entity	1.34%	1.36%
Credit and Equity Investments, Primarily in Private Equity-Owned Companies [Member]
Investment Securities [Line Items]
Carrying Value	$ 2,655	$ 1,950
Unfunded Balance	$ 2,584	$ 3,050
Percentage investment held by the entity	0.39%	0.47%