Investments (Credit Quality Indicators) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Recording investment gross of allowance for credit losses	$ 7,797,038	$ 6,160,410
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	1,788,998	1,142,205
One Year Prior	1,139,236	782,796
Two Year Prior	770,354	1,261,597
Three Year Prior	1,258,169	363,599
Four Year Prior	255,562	528,288
Prior	1,736,220	1,514,519
Revolving Loans	6,479
Recording investment gross of allowance for credit losses	6,955,018	5,593,004
Commercial mortgage loans | ≥ 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	1,728,895	1,038,315
One Year Prior	962,290	779,282
Two Year Prior	755,350	1,261,597
Three Year Prior	1,256,699	292,561
Four Year Prior	255,562	497,407
Prior	1,616,904	1,402,831
Revolving Loans	0
Recording investment gross of allowance for credit losses	6,575,700	5,271,993
Commercial mortgage loans | 1.0X to 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	60,103	103,890
One Year Prior	176,946	3,514
Two Year Prior	15,004	0
Three Year Prior	0	0
Four Year Prior	0	15,632
Prior	59,871	40,521
Revolving Loans	6,479
Recording investment gross of allowance for credit losses	318,403	163,557
Commercial mortgage 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	1,470	71,038
Four Year Prior	0	15,249
Prior	59,445	71,167
Revolving Loans	0
Recording investment gross of allowance for credit losses	60,915	157,454
Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	271,275	126,949
One Year Prior	108,965	235,585
Two Year Prior	220,325	132,042
Three Year Prior	131,581	25,875
Four Year Prior	25,145	15,824
Prior	38,478	25,771
Revolving Loans	34,272
Recording investment gross of allowance for credit losses	830,041	562,046
Agricultural Property Loans | ≥ 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	259,647	126,949
One Year Prior	95,087	233,585
Two Year Prior	211,030	130,353
Three Year Prior	129,865	24,063
Four Year Prior	23,488	15,824
Prior	38,478	25,771
Revolving Loans	18,834
Recording investment gross of allowance for credit losses	776,429	556,545
Agricultural Property Loans | 1.0X to 1.2X
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	11,628	0
One Year Prior	13,878	2,000
Two Year Prior	9,295	0
Three Year Prior	0	1,812
Four Year Prior	0	0
Prior	0	0
Revolving Loans	15,438
Recording investment gross of allowance for credit losses	50,239	3,812
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	1,689
Three Year Prior	1,716	0
Four Year Prior	1,657	0
Prior	0	0
Revolving Loans	0
Recording investment gross of allowance for credit losses	3,373	1,689
0%-59.99% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	452,940	249,037
One Year Prior	232,276	245,914
Two Year Prior	306,684	482,718
Three Year Prior	482,596	109,249
Four Year Prior	134,403	265,053
Prior	1,138,394	1,068,763
Revolving Loans	6,479
Recording investment gross of allowance for credit losses	2,753,772	2,420,734
0%-59.99% | Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	241,715	73,774
One Year Prior	89,569	179,375
Two Year Prior	163,820	132,042
Three Year Prior	126,368	25,875
Four Year Prior	23,488	15,824
Prior	38,478	25,771
Revolving Loans	18,834
Recording investment gross of allowance for credit losses	702,272	452,661
60%-69.99% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	972,161	675,153
One Year Prior	541,849	355,984
Two Year Prior	273,258	449,878
Three Year Prior	360,457	172,721
Four Year Prior	110,515	225,803
Prior	303,107	206,237
Revolving Loans	0
Recording investment gross of allowance for credit losses	2,561,347	2,085,776
60%-69.99% | Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	29,560	47,489
One Year Prior	19,396	56,210
Two Year Prior	49,210	0
Three Year Prior	0	0
Four Year Prior	0	0
Prior	0	0
Revolving Loans	0
Recording investment gross of allowance for credit losses	98,166	103,699
70%-79.99% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	362,701	218,015
One Year Prior	365,111	133,343
Two Year Prior	134,208	255,299
Three Year Prior	330,355	77,812
Four Year Prior	6,774	20,924
Prior	77,399	86,806
Revolving Loans	0
Recording investment gross of allowance for credit losses	1,276,548	792,199
70%-79.99% | Agricultural Property Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	0	5,686
One Year Prior	0	0
Two Year Prior	0	0
Three Year Prior	5,213	0
Four Year Prior	0	0
Prior	0	0
Revolving Loans	0
Recording investment gross of allowance for credit losses	5,213	5,686
80% or greater | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Year	1,196	0
One Year Prior	0	47,555
Two Year Prior	56,204	73,702
Three Year Prior	84,761	3,817
Four Year Prior	3,870	16,508
Prior	217,320	152,713
Revolving Loans	0
Recording investment gross of allowance for credit losses	363,351	294,295
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	7,295	0
Three Year Prior	0	0
Four Year Prior	1,657	0
Prior	0	0
Revolving Loans	15,438
Recording investment gross of allowance for credit losses	$ 24,390	$ 0