INVESTMENTS - Credit Quality (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	$ 17,795	$ 16,593
Total	17,742	16,577
Non-accruing Loans	53	16
Non-accruing Loans with No Allowance	3	0
Interest Income on Non-accruing Loans	1	0
Past Due
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	64	77
30-59 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	18	59
60-89 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	4	5
90 Days or More
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	42	13
Current
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	17,678	16,500
Commercial:
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	1,133	3,272
2022	3,285	2,114
2021	2,118	1,369
2020	1,367	642
2019	638	1,201
Prior	6,115	5,043
Revolving Loans Amortized Cost Basis	425	328
Revolving Loans Converted to Term Loans Amortized Cost Basis	132	34
Total	15,213	14,003
Total	15,179	14,003
Non-accruing Loans	34	0
Non-accruing Loans with No Allowance	0	0
Interest Income on Non-accruing Loans	1	0
Commercial: | Past Due
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	56
Commercial: | 30-59 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	56
Commercial: | 60-89 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	0
Commercial: | 90 Days or More
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	0
Commercial: | Current
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	15,179	13,947
Commercial: | Greater than 2.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	175	771
2022	695	1,159
2021	1,126	1,113
2020	1,140	102
2019	157	571
Prior	3,110	1,911
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	6,403	5,627
Commercial: | 1.8x to 2.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	0	158
2022	0	215
2021	181	164
2020	167	197
2019	172	186
Prior	737	477
Revolving Loans Amortized Cost Basis	256	279
Revolving Loans Converted to Term Loans Amortized Cost Basis	96	0
Total	1,609	1,676
Commercial: | 1.5x to 1.8x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	81	337
2022	799	390
2021	234	32
2020	0	153
2019	236	176
Prior	984	1,175
Revolving Loans Amortized Cost Basis	92	4
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	2,426	2,267
Commercial: | 1.2x to 1.5x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	470	1,041
2022	762	259
2021	455	0
2020	0	92
2019	30	73
Prior	761	917
Revolving Loans Amortized Cost Basis	6	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	2,484	2,382
Commercial: | 1.0x to 1.2x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	400	507
2022	674	43
2021	43	60
2020	0	98
2019	43	160
Prior	416	492
Revolving Loans Amortized Cost Basis	71	45
Revolving Loans Converted to Term Loans Amortized Cost Basis	36	34
Total	1,683	1,439
Commercial: | Less than 1.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	7	458
2022	355	48
2021	79	0
2020	60	0
2019	0	35
Prior	107	71
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	608	612
Commercial: | 0% - 50%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	250	624
2022	484	130
2021	130	0
2020	35	0
2019	0	119
Prior	1,603	1,242
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	2,502	2,115
Commercial: | 50% - 70%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	636	2,285
2022	2,313	1,569
2021	815	906
2020	869	313
2019	257	623
Prior	2,618	2,254
Revolving Loans Amortized Cost Basis	419	328
Revolving Loans Converted to Term Loans Amortized Cost Basis	96	0
Total	8,023	8,278
Commercial: | 70% - 90%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	247	363
2022	488	415
2021	1,139	463
2020	463	329
2019	289	424
Prior	1,198	1,314
Revolving Loans Amortized Cost Basis	6	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	36	34
Total	3,866	3,342
Commercial: | 90% plus
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	0	0
2022	0	0
2021	34	0
2020	0	0
2019	92	35
Prior	696	233
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	822	268
Agricultural:
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	132	353
2022	309	367
2021	348	450
2020	439	197
2019	192	215
Prior	1,130	1,008
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	2,550	2,590
Total	2,531	2,574
Non-accruing Loans	19	16
Non-accruing Loans with No Allowance	3	0
Interest Income on Non-accruing Loans	0	0
Agricultural: | Past Due
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	64	21
Agricultural: | 30-59 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	18	3
Agricultural: | 60-89 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	4	5
Agricultural: | 90 Days or More
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	42	13
Agricultural: | Current
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	2,467	2,553
Agricultural: | Greater than 2.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	7	51
2022	51	40
2021	39	62
2020	60	21
2019	20	12
Prior	184	193
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	361	379
Agricultural: | 1.8x to 2.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	16	16
2022	16	58
2021	56	35
2020	32	24
2019	23	14
Prior	62	51
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	205	198
Agricultural: | 1.5x to 1.8x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	9	69
2022	50	42
2021	31	111
2020	109	18
2019	18	19
Prior	199	196
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	416	455
Agricultural: | 1.2x to 1.5x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	38	107
2022	111	147
2021	155	177
2020	173	98
2019	99	99
Prior	374	298
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	950	926
Agricultural: | 1.0x to 1.2x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	33	91
2022	57	80
2021	63	61
2020	57	30
2019	26	60
Prior	287	257
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	523	579
Agricultural: | Less than 1.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	29	19
2022	24	0
2021	4	4
2020	8	6
2019	6	11
Prior	24	13
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	95	53
Agricultural: | 0% - 50%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	86	163
2022	163	182
2021	186	228
2020	235	129
2019	134	132
Prior	811	725
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	1,615	1,559
Agricultural: | 50% - 70%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	46	190
2022	146	185
2021	162	222
2020	204	68
2019	58	83
Prior	303	267
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	919	1,015
Agricultural: | 70% - 90%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior	16	16
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	16	16
Agricultural: | 90% plus
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	0	0
Total commercial and agricultural mortgage loans:
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	1,265	3,625
2022	3,594	2,481
2021	2,466	1,819
2020	1,806	839
2019	830	1,416
Prior	7,245	6,051
Revolving Loans Amortized Cost Basis	425	328
Revolving Loans Converted to Term Loans Amortized Cost Basis	132	34
Total	17,763	16,593
Total commercial and agricultural mortgage loans: | Greater than 2.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	182	822
2022	746	1,199
2021	1,165	1,175
2020	1,200	123
2019	177	583
Prior	3,294	2,104
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	6,764	6,006
Total commercial and agricultural mortgage loans: | 1.8x to 2.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	16	174
2022	16	273
2021	237	199
2020	199	221
2019	195	200
Prior	799	528
Revolving Loans Amortized Cost Basis	256	279
Revolving Loans Converted to Term Loans Amortized Cost Basis	96	0
Total	1,814	1,874
Total commercial and agricultural mortgage loans: | 1.5x to 1.8x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	90	406
2022	849	432
2021	265	143
2020	109	171
2019	254	195
Prior	1,183	1,371
Revolving Loans Amortized Cost Basis	92	4
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	2,842	2,722
Total commercial and agricultural mortgage loans: | 1.2x to 1.5x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	508	1,148
2022	873	406
2021	610	177
2020	173	190
2019	129	172
Prior	1,135	1,215
Revolving Loans Amortized Cost Basis	6	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	3,434	3,308
Total commercial and agricultural mortgage loans: | 1.0x to 1.2x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	433	598
2022	731	123
2021	106	121
2020	57	128
2019	69	220
Prior	703	749
Revolving Loans Amortized Cost Basis	71	45
Revolving Loans Converted to Term Loans Amortized Cost Basis	36	34
Total	2,206	2,018
Total commercial and agricultural mortgage loans: | Less than 1.0x
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	36	477
2022	379	48
2021	83	4
2020	68	6
2019	6	46
Prior	131	84
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	703	665
Total commercial and agricultural mortgage loans: | 0% - 50%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	336	787
2022	647	312
2021	316	228
2020	270	129
2019	134	251
Prior	2,414	1,967
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	4,117	3,674
Total commercial and agricultural mortgage loans: | 50% - 70%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	682	2,475
2022	2,459	1,754
2021	977	1,128
2020	1,073	381
2019	315	706
Prior	2,921	2,521
Revolving Loans Amortized Cost Basis	419	328
Revolving Loans Converted to Term Loans Amortized Cost Basis	96	0
Total	8,942	9,293
Total commercial and agricultural mortgage loans: | 70% - 90%
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	247	363
2022	488	415
2021	1,139	463
2020	463	329
2019	289	424
Prior	1,214	1,330
Revolving Loans Amortized Cost Basis	6	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	36	34
Total	3,882	3,358
Total commercial and agricultural mortgage loans: | 90% plus
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	0	0
2022	0	0
2021	34	0
2020	0	0
2019	92	35
Prior	696	233
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	822	268
Residential
Financing Receivable, before Allowance for Credit Loss [Abstract]
2023	21
2022	11
2021	0
2020	0
2019	0
Prior	0
Total	32	0
Total	32	0
Non-accruing Loans	0	0
Non-accruing Loans with No Allowance	0	0
Interest Income on Non-accruing Loans	0	0
Residential | Past Due
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	0
Residential | 30-59 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	0
Residential | 60-89 Days
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	0
Residential | 90 Days or More
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	0	0
Residential | Current
Financing Receivable, before Allowance for Credit Loss [Abstract]
Total	$ 32	$ 0