Investments - Commercial Mortgage Loan Participations, Internal Credit Assessment (Details) $ in Thousands	Dec. 31, 2021 USD ($) loan extensionOption	Dec. 31, 2020 USD ($) loan
Financing Receivable, Credit Quality Indicator [Line Items]
Less allowance for credit losses on the investment pool	$ (827)	$ (2,503)
Less allowance for credit losses on individual loans	$ 0	$ (1,002)
Commercial mortgage participations
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans	22	24
Current Fiscal Year	$ 0	$ 20,176
Fiscal Year before Current Fiscal Year	25,036	29,951
Two Years before Current Fiscal Year	33,691	52,520
Three Years before Current Fiscal Year	48,214	61,460
Four Years before Current Fiscal Year	35,729
Total commercial mortgage loans	142,670	164,107
Carrying value, net of valuation allowance	$ 141,843	$ 160,602
Commercial mortgage participations | Low
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	14	17
Current Fiscal Year	$ 0	$ 20,176
Fiscal Year before Current Fiscal Year	23,636	14,757
Two Years before Current Fiscal Year	11,925	33,132
Three Years before Current Fiscal Year	41,209	61,460
Four Years before Current Fiscal Year	35,729
Total commercial mortgage loans	$ 112,499	$ 129,525
Commercial mortgage participations | Medium
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	6	4
Current Fiscal Year	$ 0	$ 0
Fiscal Year before Current Fiscal Year	1,400	10,640
Two Years before Current Fiscal Year	17,173	7,796
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0
Total commercial mortgage loans	$ 18,573	$ 18,436
Commercial mortgage participations | High
Financing Receivable, Credit Quality Indicator [Line Items]
Number of Loans | loan	2	3
Current Fiscal Year	$ 0	$ 0
Fiscal Year before Current Fiscal Year	0	4,554
Two Years before Current Fiscal Year	4,593	11,592
Three Years before Current Fiscal Year	7,005	0
Four Years before Current Fiscal Year	0
Total commercial mortgage loans	$ 11,598	$ 16,146