Summary of Significant Accounting Policies - Adjusted Income Statement and Comprehensive Income to Apply Adopted Guidance (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Premiums	$ 7,244	$ 7,828	$ 24,782	$ 22,460
Policy fees	702	735	2,094	2,193
Total net realized gains (losses)	1,081	2,572	(1,125)	8,783
Total revenues	12,774	13,998	36,976	42,605
Policyholder benefits and losses incurred	4,982	6,049	18,237	16,093
Change in the fair value of market risk benefits, net	(418)	(435)	(484)	(713)
Interest credited to policyholder account balances	1,135	959	3,237	2,749
Amortization of deferred policy acquisition costs	1,190	1,170	3,673	3,423
General operating and other expenses	2,117	2,075	6,365	6,445
Total benefits, losses and expenses	9,206	10,094	31,772	29,062
Income (loss) from continuing operations before income tax expense (benefit)	3,568	3,904	5,204	13,543
Income tax expense (benefit)	821	817	853	2,816
Income (loss) from continuing operations	2,747	3,087	4,351	10,727
Net income (loss)	2,747	3,087	4,351	10,726
Net income (loss) from continuing operations attributable to noncontrolling interests	720	339	801	1,051
Net income (loss) attributable to AIG	2,027	2,748	3,550	9,675
Net income attributable to AIG common shareholders	$ 2,020	$ 2,741	$ 3,528	$ 9,653
Income (loss) attributable to AIG common shareholders (in dollars per share)	$ 2.83	$ 3.59	$ 4.86	$ 12.22
Net income attributable to AIG common shareholders (in dollars per share)	$ 2.81	$ 3.55	$ 4.83	$ 12.08
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 2,747	$ 3,087	$ 4,351	$ 10,726
Change in unrealized appreciation (depreciation) of fixed maturity securities on which allowance for credit losses was taken	(66)	(74)	24	(83)
Change in unrealized appreciation (depreciation) of all other investments	(5,694)	(9,504)	(3,440)	(40,427)
Change in fair value of market risk benefits attributable to changes in our own credit risk	(81)	253	(196)	1,617
Change in the discount rates used to measure traditional and limited payment long-duration insurance contracts	1,147	1,725	1,100	5,885
Change in foreign currency translation adjustments	(269)	(721)	(356)	(1,062)
Other comprehensive income (loss)	(4,918)	(8,306)	(2,743)	(34,034)
Comprehensive income (loss)	(2,171)	(5,219)	1,608	(23,308)
Comprehensive income (loss) attributable to noncontrolling interests	(712)	(378)	(263)	(1,676)
Comprehensive income (loss) attributable to AIG	$ (1,459)	(4,841)	$ 1,871	(21,632)
As Previously Reported
Income Statement [Abstract]
Premiums		7,832		22,458
Policy fees		732		2,238
Total net realized gains (losses)		3,175		10,986
Total revenues		14,602		44,851
Policyholder benefits and losses incurred		6,187		16,565
Change in the fair value of market risk benefits, net		0		0
Interest credited to policyholder account balances		951		2,738
Amortization of deferred policy acquisition costs		1,248		3,983
General operating and other expenses		2,093		6,497
Total benefits, losses and expenses		10,755		30,848
Income (loss) from continuing operations before income tax expense (benefit)		3,847		14,003
Income tax expense (benefit)		806		2,913
Income (loss) from continuing operations		3,041		11,090
Net income (loss)		3,041		11,089
Net income (loss) from continuing operations attributable to noncontrolling interests		332		1,084
Net income (loss) attributable to AIG		2,709		10,005
Net income attributable to AIG common shareholders		$ 2,702		$ 9,983
Income (loss) attributable to AIG common shareholders (in dollars per share)		$ 3.54		$ 12.64
Net income attributable to AIG common shareholders (in dollars per share)		$ 3.50		$ 12.49
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 3,041		$ 11,089
Change in unrealized appreciation (depreciation) of fixed maturity securities on which allowance for credit losses was taken		(73)		(78)
Change in unrealized appreciation (depreciation) of all other investments		(8,324)		(34,469)
Change in fair value of market risk benefits attributable to changes in our own credit risk		0		0
Change in the discount rates used to measure traditional and limited payment long-duration insurance contracts		0		0
Change in foreign currency translation adjustments		(591)		(877)
Other comprehensive income (loss)		(8,973)		(35,388)
Comprehensive income (loss)		(5,932)		(24,299)
Comprehensive income (loss) attributable to noncontrolling interests		(464)		(1,784)
Comprehensive income (loss) attributable to AIG		(5,468)		(22,515)
Effect of Change
Income Statement [Abstract]
Premiums		(4)		2
Policy fees		3		(45)
Total net realized gains (losses)		(603)		(2,203)
Total revenues		(604)		(2,246)
Policyholder benefits and losses incurred		(138)		(472)
Change in the fair value of market risk benefits, net		(435)		(713)
Interest credited to policyholder account balances		8		11
Amortization of deferred policy acquisition costs		(78)		(560)
General operating and other expenses		(18)		(52)
Total benefits, losses and expenses		(661)		(1,786)
Income (loss) from continuing operations before income tax expense (benefit)		57		(460)
Income tax expense (benefit)		11		(97)
Income (loss) from continuing operations		46		(363)
Net income (loss)		46		(363)
Net income (loss) from continuing operations attributable to noncontrolling interests		7		(33)
Net income (loss) attributable to AIG		39		(330)
Net income attributable to AIG common shareholders		$ 39		$ (330)
Income (loss) attributable to AIG common shareholders (in dollars per share)		$ 0.05		$ (0.42)
Net income attributable to AIG common shareholders (in dollars per share)		$ 0.05		$ (0.41)
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 46		$ (363)
Change in unrealized appreciation (depreciation) of fixed maturity securities on which allowance for credit losses was taken		(1)		(5)
Change in unrealized appreciation (depreciation) of all other investments		(1,180)		(5,958)
Change in fair value of market risk benefits attributable to changes in our own credit risk		253		1,617
Change in the discount rates used to measure traditional and limited payment long-duration insurance contracts		1,725		5,885
Change in foreign currency translation adjustments		(130)		(185)
Other comprehensive income (loss)		667		1,354
Comprehensive income (loss)		713		991
Comprehensive income (loss) attributable to noncontrolling interests		86		108
Comprehensive income (loss) attributable to AIG		$ 627		$ 883