Investment Information - Allowance for expected credit losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Allowance for expected credit losses
Balance at beginning of period		$ 58,410	$ 2,124	$ 2,883	$ 2,397
Additions for current-period provision for expected credit losses		3,780	48	53,521	2,710
Additions (reductions) for previously recognized expected credit losses		(12,530)	405	(5,609)	(1,317)
Reductions due to disposals		(3,667)	(466)	(4,802)	(1,679)
Balance at end of period		45,993	2,111	45,993	2,111
Structured securities
Allowance for expected credit losses
Balance at beginning of period	[1]	18,283	759	802	1,490
Additions for current-period provision for expected credit losses	[1]	1,782	48	12,560	282
Additions (reductions) for previously recognized expected credit losses	[1]	(9,767)	14	(2,575)	(751)
Reductions due to disposals	[1]	(1,780)	(234)	(2,269)	(434)
Balance at end of period	[1]	8,518	587	8,518	587
Municipal bonds
Allowance for expected credit losses
Balance at beginning of period		298	6	2	11
Additions for current-period provision for expected credit losses		12	0	359	0
Additions (reductions) for previously recognized expected credit losses		(211)	(4)	(262)	(9)
Reductions due to disposals		0	0	0	0
Balance at end of period		99	2	99	2
Corporate bonds
Allowance for expected credit losses
Balance at beginning of period		39,829	1,359	2,079	896
Additions for current-period provision for expected credit losses		1,986	0	40,602	2,428
Additions (reductions) for previously recognized expected credit losses		(2,552)	395	(2,772)	(557)
Reductions due to disposals		(1,887)	(232)	(2,533)	(1,245)
Balance at end of period		$ 37,376	$ 1,522	$ 37,376	$ 1,522

[1] Includes asset backed securities, residential mortgage backed securities and commercial mortgage backed securities.