Investment Information - Allowance for expected credit losses (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Allowance for expected credit losses
Balance at beginning of period		$ 2,883	$ 2,397
Additions for current-period provision for expected credit losses		31,235	2,603
Additions (reductions) for previously recognized expected credit losses		481	(931)
Reductions due to disposals		(454)	(239)
Balance at end of period		34,145	3,830
Structured securities
Allowance for expected credit losses
Balance at beginning of period	[1]	802	1,490
Additions for current-period provision for expected credit losses	[1]	5,990	182
Additions (reductions) for previously recognized expected credit losses	[1]	487	(382)
Reductions due to disposals	[1]	(281)	(83)
Balance at end of period	[1]	6,998	1,207
Municipal bonds
Allowance for expected credit losses
Balance at beginning of period		2	11
Additions for current-period provision for expected credit losses		95	0
Additions (reductions) for previously recognized expected credit losses		9	(9)
Reductions due to disposals		0	0
Balance at end of period		106	2
Corporate bonds
Allowance for expected credit losses
Balance at beginning of period		2,079	896
Additions for current-period provision for expected credit losses		25,150	2,421
Additions (reductions) for previously recognized expected credit losses		(15)	(540)
Reductions due to disposals		(173)	(156)
Balance at end of period		$ 27,041	$ 2,621

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