Investments (Amortized Cost and Fair Value of Fixed Maturities by Contractual Maturities) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Available for Sale, Amortized Cost
Due in one year or less		$ 12,287
Due after one year through five years		51,942
Due after five years through ten years		68,965
Due after ten years		182,291
Amortized Cost		346,574	$ 331,745
Available-for-Sale, Fair Value
Due in one year or less		12,816
Due after one year through five years		55,160
Due after five years through ten years		75,506
Due after ten years		215,665
Fair Value	[1]	391,096	353,656
Held-to-Maturity, Amortized Cost
Due in one year or less		29
Due after one year through five years		114
Due after five years through ten years		592
Due after ten years		888
Amortized Cost	[1]	1,933	2,013
Held-to-Maturity, Fair Value
Due in one year or less		29
Due after one year through five years		116
Due after five years through ten years		657
Due after ten years		1,169
Fixed maturities, held to maturity, fair value		2,302	2,372
Asset-backed securities
Available for Sale, Amortized Cost
Debt Maturities, without single maturity date		13,067
Available-for-Sale, Fair Value
Debt Maturities, without Single Maturity Date		13,174
Held-to-Maturity, Amortized Cost
Debt Maturities, without Single Maturity Date		0
Held-to-Maturity, Fair Value
Debt Maturities, without Single Maturity Date		0
Commercial mortgage-backed securities
Available for Sale, Amortized Cost
Debt Maturities, without single maturity date		14,978
Available-for-Sale, Fair Value
Debt Maturities, without Single Maturity Date		15,574
Held-to-Maturity, Amortized Cost
Debt Maturities, without Single Maturity Date		0
Held-to-Maturity, Fair Value
Debt Maturities, without Single Maturity Date		0
Residential mortgage-backed securities
Available for Sale, Amortized Cost
Debt Maturities, without single maturity date		3,044
Available-for-Sale, Fair Value
Debt Maturities, without Single Maturity Date		3,201
Held-to-Maturity, Amortized Cost
Debt Maturities, without Single Maturity Date		310
Held-to-Maturity, Fair Value
Debt Maturities, without Single Maturity Date		331
Prudential Netting Agreement | U.S. private corporate securities
Available-for-Sale, Fair Value
Fair Value		4,751	4,216
Fixed maturities
Available for Sale, Amortized Cost
Amortized Cost		346,574	331,745
Available-for-Sale, Fair Value
Fair Value		391,096	353,656
Held-to-Maturity, Amortized Cost
Amortized Cost		1,933	2,013
Held-to-Maturity, Fair Value
Fixed maturities, held to maturity, fair value		2,302	2,372
Fixed maturities | U.S. private corporate securities
Available for Sale, Amortized Cost
Amortized Cost		34,410	32,450
Available-for-Sale, Fair Value
Fair Value		36,533	33,020
Fixed maturities | Asset-backed securities
Available for Sale, Amortized Cost
Amortized Cost		13,067	12,888
Available-for-Sale, Fair Value
Fair Value		13,174	12,973
Fixed maturities | Commercial mortgage-backed securities
Available for Sale, Amortized Cost
Amortized Cost		14,978	13,396
Available-for-Sale, Fair Value
Fair Value		15,574	13,315
Fixed maturities | Residential mortgage-backed securities
Available for Sale, Amortized Cost
Amortized Cost		3,044	2,937
Available-for-Sale, Fair Value
Fair Value		3,201	3,004
Held-to-Maturity, Amortized Cost
Amortized Cost		310	365
Held-to-Maturity, Fair Value
Fixed maturities, held to maturity, fair value		331	388
Fixed maturities | Foreign private corporate securities
Available for Sale, Amortized Cost
Amortized Cost		27,619	25,314
Available-for-Sale, Fair Value
Fair Value		28,240	24,531
Held-to-Maturity, Amortized Cost
Amortized Cost		83	95
Held-to-Maturity, Fair Value
Fixed maturities, held to maturity, fair value		85	98
Fixed maturities | Prudential Netting Agreement
Held-to-Maturity, Amortized Cost
Amortized Cost		4,998	4,879
Held-to-Maturity, Fair Value
Fixed maturities, held to maturity, fair value		5,401	4,879
Fixed maturities | Prudential Netting Agreement | U.S. private corporate securities
Available for Sale, Amortized Cost
Amortized Cost		4,751	4,216
Available-for-Sale, Fair Value
Fair Value		$ 4,757	$ 4,216

[1] See Note 4 for details of balances associated with variable interest entities.