Fair value measurements - Value of Assets and Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Carrying value
Other invested assets	$ 37,524	$ 26,419
Total financial assets	1,558,905	1,600,718
Debt obligations	92,194
Total financial liabilities	1,491,469	1,509,762
Asset Management
Carrying value
Other invested assets	12,908	11,165
Total financial assets	59,292	66,423
Total financial liabilities	111,991	97,609
Insurance Solutions
Carrying value
Other invested assets	24,616	15,254
Total financial assets	1,499,613	1,534,295
Interest sensitive contract liabilities	360,462	363,981
Total financial liabilities	1,379,478	1,412,153
Fair value
Corporate loans	397,302	405,621
Amortized cost
Carrying value
Total financial assets	205,644	192,950
Total financial liabilities	469,906	457,481
Amortized cost | Asset Management
Carrying value
Debt obligations	92,194	76,250
Total financial liabilities	92,194	76,250
Amortized cost | Insurance Solutions
Carrying value
Other invested assets	15,321	17,097
Total financial assets	192,353	179,663
Mortgage loans	177,032	162,566
Debt obligations	17,250	17,250
Interest sensitive contract liabilities	360,462	363,981
Total financial liabilities	377,712	381,231
Other than Fair Value Measurement
Fair value
Total	209,217	201,241
Total financial liabilities	464,652	454,308
Other than Fair Value Measurement | Asset Management
Fair value
Debt obligation	86,788	72,880
Total financial liabilities	86,788	72,880
Other than Fair Value Measurement | Insurance Solutions
Fair value
Mortgage loans	182,712	172,602
Other invested assets	15,378	17,488
Total	198,090	190,090
Debt obligation	17,402	17,447
Interest sensitive contract liabilities	360,462	363,981
Total financial liabilities	377,864	381,428
Other than Fair Value Measurement | Level 1
Fair value
Total financial liabilities	37,184
Other than Fair Value Measurement | Level 1 | Asset Management
Fair value
Debt obligation	37,184
Total financial liabilities	37,184
Other than Fair Value Measurement | Level 2
Fair value
Total financial liabilities	360,462	363,981
Other than Fair Value Measurement | Level 2 | Insurance Solutions
Fair value
Interest sensitive contract liabilities	360,462	363,981
Total financial liabilities	360,462	363,981
Other than Fair Value Measurement | Level 3
Fair value
Total	209,217	201,241
Total financial liabilities	67,006	90,327
Other than Fair Value Measurement | Level 3 | Asset Management
Fair value
Debt obligation	49,604	72,880
Total financial liabilities	49,604	72,880
Other than Fair Value Measurement | Level 3 | Insurance Solutions
Fair value
Mortgage loans	182,712	172,602
Other invested assets	15,378	17,488
Total	198,090	190,090
Debt obligation	17,402	17,447
Total financial liabilities	17,402	17,447
Corporate | Insurance Solutions
Fair value
Corporate loans	158,528	166,693
Corporate | Amortized cost | Asset Management
Carrying value
Corporate loans	13,291	13,287
Total financial assets	13,291	13,287
Corporate | Other than Fair Value Measurement | Asset Management
Fair value
Corporate loans	11,127	11,151
Total	11,127	11,151
Corporate | Other than Fair Value Measurement | Level 3 | Asset Management
Fair value
Corporate loans	11,127	11,151
Total	$ 11,127	$ 11,151