Investments (excluding Consolidated Investment Entities) - Debt Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale Securities, Including Securities Pledged [Line Items]
Fixed maturities, amortized cost	$ 36,974	$ 35,836
Fixed maturities, available-for-sale, at fair value	42,330	39,663
Fixed maturities
Available-for-sale Securities, Including Securities Pledged [Line Items]
One year or less, Amortized Cost	1,255
One year or less, Fair Value	1,266
After one year through five years, Amortized Cost	4,982
After one year through five years, Fair Value	5,311
After five years through ten years, Amortized Cost	7,561
After five years through ten years, Fair Value	8,529
After ten years, Amortized Cost	15,331
After ten years, Fair Value	19,077
Fixed maturities, amortized cost	40,665	39,807
Fixed maturities, available-for-sale, at fair value	46,171	43,778
Mortgage-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Without single maturity date, Amortized Cost	9,441
Without single maturity date, Fair Value	9,898
Other asset-backed securities
Available-for-sale Securities, Including Securities Pledged [Line Items]
Without single maturity date, Amortized Cost	2,095
Without single maturity date, Fair Value	2,090
Fixed maturities, amortized cost	2,095	2,058
Fixed maturities, available-for-sale, at fair value	$ 2,090	$ 2,055