Fair Value Measurements - Investments in certain other invested assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Private Equity Funds and Hedge Funds
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	$ 9,822	$ 8,418
Unfunded Commitments	4,064	3,330
Private equity funds
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	8,428	6,588
Unfunded Commitments	$ 4,064	3,330
Average original expected lives (in years)	10 years
Private equity funds | Minimum
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Extension period (in years)	1 year
Private equity funds | Maximum
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Extension period (in years)	2 years
Leveraged buyout
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	$ 3,146	2,768
Unfunded Commitments	2,448	1,798
Real assets
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	1,851	904
Unfunded Commitments	840	487
Venture capital
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	272	252
Unfunded Commitments	183	201
Growth equity
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	732	914
Unfunded Commitments	60	82
Mezzanine
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	598	534
Unfunded Commitments	142	354
Other
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	1,829	1,216
Unfunded Commitments	391	408
Hedge funds
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	1,394	1,830
Unfunded Commitments	0	0
Event-driven
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	92	466
Unfunded Commitments	0	0
Long-short
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	696	432
Unfunded Commitments	0	0
Macro
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	414	516
Unfunded Commitments	0	0
Other
INVESTMENTS IN CERTAIN ENTITIES CARRIED AT FAIR VALUE USING NET ASSET VALUE PER SHARE
Fair Value Using NAV Per Share (or its equivalent)	192	416
Unfunded Commitments	$ 0	$ 0