Net gains (losses) from investment activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Investments
Net realized gains (losses)	$ (1,546)	$ (296)
Net unrealized gains (losses)	(12,036)	1,332
Asset Management
Investments
Net realized gains (losses)	367	60
Net unrealized gains (losses)	(723)	781
Credit releases (losses)	5	0
Realized gain/(loss) on investments	(351)	841
Asset Management | Corporate loans
Investments
Net realized gains (losses)	0	0
Net unrealized gains (losses)	0	0
Credit releases (losses)	5	0
Realized gain/(loss) on investments	5	0
Asset Management | Equity securities
Investments
Net realized gains (losses)	367	60
Net unrealized gains (losses)	(719)	(187)
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(352)	(127)
Asset Management | Derivatives
Investments
Net realized gains (losses)	0	0
Net unrealized gains (losses)	(2)	0
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(2)	0
Asset Management | Other
Investments
Net realized gains (losses)	0	0
Net unrealized gains (losses)	(2)	0
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(2)	0
Asset Management | Debt obligation
Investments
Net realized gains (losses)	0	0
Net unrealized gains (losses)	0	968
Credit releases (losses)	0	0
Realized gain/(loss) on investments	0	968
Insurance Solutions | Consolidated Entity, Excluding Consolidated VIE
Investments
Net realized gains (losses)	(1,207)	(416)
Net unrealized gains (losses)	(8,342)	1,846
Credit releases (losses)	4,535	42
Realized gain/(loss) on investments	(5,014)	1,472
Insurance Solutions | Variable Interest Entity, Primary Beneficiary
Investments
Net realized gains (losses)	(706)	60
Net unrealized gains (losses)	(2,971)	(326)
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(3,677)	(266)
Insurance Solutions | Consolidated Balance Including Variable Interest Entity
Investments
Net realized gains (losses)	(1,913)	(356)
Net unrealized gains (losses)	(11,313)	1,520
Credit releases (losses)	4,535	42
Realized gain/(loss) on investments	(8,691)	1,206
Insurance Solutions | Corporate loans
Investments
Net realized gains (losses)	0	2
Net unrealized gains (losses)	(400)	789
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(400)	791
Insurance Solutions | Equity securities
Investments
Net realized gains (losses)	3,597	(246)
Net unrealized gains (losses)	(3,305)	90
Credit releases (losses)	0	0
Realized gain/(loss) on investments	292	(156)
Insurance Solutions | Other
Investments
Net realized gains (losses)	0	0
Net unrealized gains (losses)	(11)	(390)
Credit releases (losses)	131	30
Realized gain/(loss) on investments	120	(360)
Insurance Solutions | U.S. state, territories and municipalities
Investments
Net realized gains (losses)	(5)	(4)
Net unrealized gains (losses)	(15)	57
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(20)	53
Insurance Solutions | Other government and agency
Investments
Net realized gains (losses)	0	0
Net unrealized gains (losses)	(28)	(1)
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(28)	(1)
Insurance Solutions | Corporate
Investments
Net realized gains (losses)	32	(10)
Net unrealized gains (losses)	(2,404)	1,186
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(2,372)	1,176
Insurance Solutions | Asset and mortgage-backed securities
Investments
Net realized gains (losses)	(210)	(158)
Net unrealized gains (losses)	(2,179)	115
Credit releases (losses)	0	0
Realized gain/(loss) on investments	(2,389)	(43)
Insurance Solutions | Mortgage loans
Investments
Net realized gains (losses)	(4,621)	0
Net unrealized gains (losses)	0	0
Credit releases (losses)	4,404	12
Realized gain/(loss) on investments	$ (217)	$ 12