Policyholders' Liabilities (Guaranteed Minimum Crediting Rate) (Details) $ in Thousands	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)		Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 49,662,070	$ 41,912,536	[1]	$ 40,752,545
1 - 50 bps above guaranteed minimum | Minimum
Policyholder Account Balance [Line Items]
Policyholder account balance above guaranteed minimum crediting rate	1			1
1 - 50 bps above guaranteed minimum | Maximum
Policyholder Account Balance [Line Items]
Policyholder account balance above guaranteed minimum crediting rate	50			50
51 - 150 bps above guaranteed minimum | Minimum
Policyholder Account Balance [Line Items]
Policyholder account balance above guaranteed minimum crediting rate	51			51
51 - 150 bps above guaranteed minimum | Maximum
Policyholder Account Balance [Line Items]
Policyholder account balance above guaranteed minimum crediting rate	150			150
Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Policyholder account balance above guaranteed minimum crediting rate	150			150
Fixed Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 2,025,288	3,575,824		$ 1,015,314	$ 3,005,867
Fixed Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	809,130			773,676
Fixed Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	543,890			66,011
Fixed Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	557,281			127,370
Fixed Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	114,987			48,257
Variable Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	3,004,628	16,432,032		3,314,888	11,465,411
Variable Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,151,143			2,423,778
Variable Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	831,156			871,922
Variable Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	22,327			19,186
Variable Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2			2
Variable/Universal Life
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	17,508,112	$ 18,736,365		16,620,170	$ 18,762,548
Variable/Universal Life | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	6,369,424			6,991,609
Variable/Universal Life | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	3,659,309			15,091
Variable/Universal Life | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	6,421,265			5,455,719
Variable/Universal Life | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 1,058,114			$ 4,157,751
Less than 1.00% | Fixed Annuities
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.00%			1.00%
Account Values with Crediting Rates	$ 21,184			$ 0
Less than 1.00% | Fixed Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	85			0
Less than 1.00% | Fixed Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	188			0
Less than 1.00% | Fixed Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	430			0
Less than 1.00% | Fixed Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 20,481			$ 0
Less than 1.00% | Variable Annuities
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.00%			1.00%
Account Values with Crediting Rates	$ 1,783,764			$ 1,922,831
Less than 1.00% | Variable Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	944,205			1,034,346
Less than 1.00% | Variable Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	821,295			869,636
Less than 1.00% | Variable Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	18,262			18,847
Less than 1.00% | Variable Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 2			$ 2
Less than 1.00% | Variable/Universal Life
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.00%			1.00%
Account Values with Crediting Rates	$ 217,003			$ 14,603
Less than 1.00% | Variable/Universal Life | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			14,603
Less than 1.00% | Variable/Universal Life | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Less than 1.00% | Variable/Universal Life | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Less than 1.00% | Variable/Universal Life | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	217,003			0
1.00% - 1.99% | Fixed Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 890,986			$ 761,950
1.00% - 1.99% | Fixed Annuities | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.00%			1.00%
1.00% - 1.99% | Fixed Annuities | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.99%			1.99%
1.00% - 1.99% | Fixed Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 497,237			$ 520,312
1.00% - 1.99% | Fixed Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	74,579			66,011
1.00% - 1.99% | Fixed Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	237,130			127,370
1.00% - 1.99% | Fixed Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	82,040			48,257
1.00% - 1.99% | Variable Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 225,030			$ 249,595
1.00% - 1.99% | Variable Annuities | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.00%			1.00%
1.00% - 1.99% | Variable Annuities | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.99%			1.99%
1.00% - 1.99% | Variable Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 221,831			$ 247,033
1.00% - 1.99% | Variable Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,113			2,223
1.00% - 1.99% | Variable Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	1,086			339
1.00% - 1.99% | Variable Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
1.00% - 1.99% | Variable/Universal Life
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 3,285,704			$ 3,070,719
1.00% - 1.99% | Variable/Universal Life | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.00%			1.00%
1.00% - 1.99% | Variable/Universal Life | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	1.99%			1.99%
1.00% - 1.99% | Variable/Universal Life | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 185,341			$ 323,385
1.00% - 1.99% | Variable/Universal Life | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
1.00% - 1.99% | Variable/Universal Life | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,528,250			733,182
1.00% - 1.99% | Variable/Universal Life | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	572,113			2,014,152
2.00% - 2.99% | Fixed Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 1,082,070			$ 212,983
2.00% - 2.99% | Fixed Annuities | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	2.00%			2.00%
2.00% - 2.99% | Fixed Annuities | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	2.99%			2.99%
2.00% - 2.99% | Fixed Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 280,760			$ 212,983
2.00% - 2.99% | Fixed Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	469,123			0
2.00% - 2.99% | Fixed Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	319,721			0
2.00% - 2.99% | Fixed Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	12,466			0
2.00% - 2.99% | Variable Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 33,630			$ 29,362
2.00% - 2.99% | Variable Annuities | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	2.00%			2.00%
2.00% - 2.99% | Variable Annuities | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	2.99%			2.99%
2.00% - 2.99% | Variable Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 26,319			$ 29,299
2.00% - 2.99% | Variable Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	4,332			63
2.00% - 2.99% | Variable Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,979			0
2.00% - 2.99% | Variable Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
2.00% - 2.99% | Variable/Universal Life
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 4,493,270			$ 4,421,311
2.00% - 2.99% | Variable/Universal Life | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	2.00%			2.00%
2.00% - 2.99% | Variable/Universal Life | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	2.99%			2.99%
2.00% - 2.99% | Variable/Universal Life | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 27,536			$ 8,479
2.00% - 2.99% | Variable/Universal Life | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	1,418,150			3,540
2.00% - 2.99% | Variable/Universal Life | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,778,586			2,405,601
2.00% - 2.99% | Variable/Universal Life | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	268,998			2,003,691
3.00% - 4.00% | Fixed Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 31,048			$ 40,381
3.00% - 4.00% | Fixed Annuities | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	3.00%			3.00%
3.00% - 4.00% | Fixed Annuities | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	4.00%			4.00%
3.00% - 4.00% | Fixed Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 31,048			$ 40,381
3.00% - 4.00% | Fixed Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
3.00% - 4.00% | Fixed Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
3.00% - 4.00% | Fixed Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
3.00% - 4.00% | Variable Annuities
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 960,177			$ 1,110,933
3.00% - 4.00% | Variable Annuities | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	3.00%			3.00%
3.00% - 4.00% | Variable Annuities | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	4.00%			4.00%
3.00% - 4.00% | Variable Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 956,761			$ 1,110,933
3.00% - 4.00% | Variable Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	3,416			0
3.00% - 4.00% | Variable Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
3.00% - 4.00% | Variable Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
3.00% - 4.00% | Variable/Universal Life
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 7,364,379			$ 7,028,360
3.00% - 4.00% | Variable/Universal Life | Minimum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	3.00%			3.00%
3.00% - 4.00% | Variable/Universal Life | Maximum
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	4.00%			4.00%
3.00% - 4.00% | Variable/Universal Life | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 4,008,791			$ 4,559,965
3.00% - 4.00% | Variable/Universal Life | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,241,159			11,551
3.00% - 4.00% | Variable/Universal Life | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	1,114,429			2,316,936
3.00% - 4.00% | Variable/Universal Life | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 0			$ 139,908
Greater than 4.00% | Fixed Annuities
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	4.00%			4.00%
Account Values with Crediting Rates	$ 0			$ 0
Greater than 4.00% | Fixed Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Greater than 4.00% | Fixed Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Greater than 4.00% | Fixed Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Greater than 4.00% | Fixed Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 0			$ 0
Greater than 4.00% | Variable Annuities
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	4.00%			4.00%
Account Values with Crediting Rates	$ 2,027			$ 2,167
Greater than 4.00% | Variable Annuities | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,027			2,167
Greater than 4.00% | Variable Annuities | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Greater than 4.00% | Variable Annuities | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Greater than 4.00% | Variable Annuities | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 0			$ 0
Greater than 4.00% | Variable/Universal Life
Policyholder Account Balance [Line Items]
Range of Guaranteed Minimum Crediting Rates	4.00%			4.00%
Account Values with Crediting Rates	$ 2,147,756			$ 2,085,177
Greater than 4.00% | Variable/Universal Life | At guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	2,147,756			2,085,177
Greater than 4.00% | Variable/Universal Life | 1 - 50 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Greater than 4.00% | Variable/Universal Life | 51 - 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	0			0
Greater than 4.00% | Variable/Universal Life | Greater than 150 bps above guaranteed minimum
Policyholder Account Balance [Line Items]
Account Values with Crediting Rates	$ 0			$ 0

[1] Prior period amounts adjusted for the implementation of Accounting Standard Update ("ASU") 2018-12: Targeted Improvements to the Accounting for Long-Duration Contracts.