Investments (Credit Quality Indicators) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Recording investment gross of allowance for credit losses	$ 2,838,511	$ 1,293,398
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	518,611	144,247
One Year Prior	311,413	178,714
Two Year Prior	544,189	197,134
Three Year Prior	260,828	178,575
Four Year Prior	309,083	264,083
Prior	722,051	311,068
Recording investment gross of allowance for credit losses	2,666,175	1,273,821
Commercial mortgage loans | ≥ 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	501,456	128,839
One Year Prior	195,164	159,476
Two Year Prior	481,289	177,098
Three Year Prior	253,938	171,255
Four Year Prior	289,443	238,010
Prior	638,092	290,741
Recording investment gross of allowance for credit losses	2,359,382	1,165,419
Commercial mortgage loans | 1.0X to 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	17,155	15,408
One Year Prior	109,862	10,334
Two Year Prior	39,577	7,134
Three Year Prior	6,890	7,320
Four Year Prior	7,100	26,073
Prior	39,213	16,418
Recording investment gross of allowance for credit losses	219,797	82,687
Commercial mortgage loans | Less than 1.0X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	0
One Year Prior	6,387	8,904
Two Year Prior	23,323	12,902
Three Year Prior	0	0
Four Year Prior	12,540	0
Prior	44,746	3,909
Recording investment gross of allowance for credit losses	86,996	25,715
Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	98,579	0
One Year Prior	26,581	0
Two Year Prior	16,226	0
Three Year Prior	6,463	6,486
Four Year Prior	8,372	0
Prior	16,115	13,091
Recording investment gross of allowance for credit losses	172,336	19,577
Agricultural Property Loans | ≥ 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	98,579	0
One Year Prior	26,581	0
Two Year Prior	16,226	0
Three Year Prior	6,463	6,486
Four Year Prior	8,372	0
Prior	15,300	12,276
Recording investment gross of allowance for credit losses	171,521	18,762
Agricultural Property Loans | 1.0X to 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	0
One Year Prior	0	0
Two Year Prior	0	0
Three Year Prior	0	0
Four Year Prior	0	0
Prior	0	0
Recording investment gross of allowance for credit losses	0	0
Agricultural Property Loans | Less than 1.0X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	0
One Year Prior	0	0
Two Year Prior	0	0
Three Year Prior	0	0
Four Year Prior	0	0
Prior	815	815
Recording investment gross of allowance for credit losses	815	815
0%-59.99% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	47,161	10,645
One Year Prior	0	47,284
Two Year Prior	179,682	33,443
Three Year Prior	76,656	92,410
Four Year Prior	126,934	162,030
Prior	553,022	251,903
Recording investment gross of allowance for credit losses	983,455	597,715
0%-59.99% | Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	98,579	0
One Year Prior	26,581	0
Two Year Prior	16,226	0
Three Year Prior	6,463	6,486
Four Year Prior	8,372	0
Prior	16,115	13,091
Recording investment gross of allowance for credit losses	172,336	19,577
60%-69.99% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	307,999	69,819
One Year Prior	225,330	95,331
Two Year Prior	289,322	141,260
Three Year Prior	170,444	52,710
Four Year Prior	126,159	80,875
Prior	116,654	43,823
Recording investment gross of allowance for credit losses	1,235,908	483,818
60%-69.99% | Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	0
One Year Prior	0	0
Two Year Prior	0	0
Three Year Prior	0	0
Four Year Prior	0	0
Prior	0	0
Recording investment gross of allowance for credit losses	0	0
70%-79.99% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	163,451	63,783
One Year Prior	86,083	36,099
Two Year Prior	75,185	22,431
Three Year Prior	13,728	32,476
Four Year Prior	55,032	21,178
Prior	51,203	15,342
Recording investment gross of allowance for credit losses	444,682	191,309
70%-79.99% | Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	0
One Year Prior	0	0
Two Year Prior	0	0
Three Year Prior	0	0
Four Year Prior	0	0
Prior	0	0
Recording investment gross of allowance for credit losses	0	0
80% or greater | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	0
One Year Prior	0	0
Two Year Prior	0	0
Three Year Prior	0	979
Four Year Prior	958	0
Prior	1,172	0
Recording investment gross of allowance for credit losses	2,130	979
80% or greater | Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	0
One Year Prior	0	0
Two Year Prior	0	0
Three Year Prior	0	0
Four Year Prior	0	0
Prior	0	0
Recording investment gross of allowance for credit losses	$ 0	$ 0