Summary of Significant Accounting Policies - Adjusted Balance Sheet to Apply Adopted Guidance (Details) - USD ($) $ in Millions	Sep. 30, 2023		Jun. 30, 2023	Dec. 31, 2022		Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	[2]	Jan. 01, 2021	Dec. 31, 2020
Assets:
Premiums and other receivables, net of allowance for credit losses and disputes of $141 in 2023 and $169 in 2022	$ 11,388			$ 13,243
Reinsurance assets, net of allowance for credit losses and disputes											$ 3,176
Deferred income taxes	14,612			14,804						$ 12,963
Deferred policy acquisition costs	11,999			12,857						12,955
Market risk benefit assets, at fair value	978			796						338	338
Other assets	11,857	[1]		12,384	[1]					13,520
Total assets	521,521			522,228						598,841
Liabilities:
Future policy benefits for life and accident and health insurance contracts	51,666			51,914		$ 49,337				67,364
Policyholder contract deposits	159,737			155,984		154,852				148,223
Market risk benefit liabilities, at fair value	4,519			4,736						8,739	8,739
Other policyholder funds	3,365			3,463						3,796
Other liabilities(c)	24,202	[1]		26,757	[1]					27,520
Total liabilities	478,308			478,774						532,906
Additional paid-in capital	77,764			79,915
Retained earnings	37,689			34,893						16,437
Accumulated other comprehensive loss	(22,529)			(22,616)						11,314
Total AIG shareholders’ equity	39,984			40,970						65,098
Non-redeemable noncontrolling interests	3,229			2,484
Total equity	43,213		$ 46,491	43,454		$ 42,113	$ 47,224	$ 69,034		65,935
Total liabilities and equity	521,521			522,228						598,841
Fortitude RE
Assets:
Reinsurance assets, net of allowance for credit losses and disputes	28,895			30,751						42,244	36,801
Excluding Fortitude
Assets:
Reinsurance assets, net of allowance for credit losses and disputes	$ 38,163			38,971						39,432	36,300
As Previously Reported
Assets:
Reinsurance assets, net of allowance for credit losses and disputes											2,707
Deferred income taxes				15,144						12,624
Deferred policy acquisition costs				15,518						9,805
Market risk benefit assets, at fair value				0						0
Other assets				12,714						13,122
Total assets				526,634						586,481
Liabilities:
Future policy benefits for life and accident and health insurance contracts				59,223						56,878
Policyholder contract deposits				158,891						154,470
Market risk benefit liabilities, at fair value				0						0
Other policyholder funds				3,909						3,548
Other liabilities(c)				26,456						27,122
Total liabilities				484,399						519,282
Additional paid-in capital				80,284
Retained earnings				33,032						15,504
Accumulated other comprehensive loss				(22,092)						13,511
Total AIG shareholders’ equity				40,002						66,362
Non-redeemable noncontrolling interests				2,233
Total equity				42,235						67,199
Total liabilities and equity				526,634						586,481
As Previously Reported | Fortitude RE
Assets:
Reinsurance assets, net of allowance for credit losses and disputes				32,159						34,578	$ 29,135
As Previously Reported | Excluding Fortitude
Assets:
Reinsurance assets, net of allowance for credit losses and disputes				39,434						38,963
Cumulative effect adjustments
Assets:
Deferred income taxes				(340)						339
Deferred policy acquisition costs				(2,661)						3,150
Market risk benefit assets, at fair value				796						338
Other assets				(330)						398
Total assets				(4,406)						12,360
Liabilities:
Future policy benefits for life and accident and health insurance contracts				(7,309)						10,486
Policyholder contract deposits				(2,907)						(6,247)
Market risk benefit liabilities, at fair value				4,736						8,739
Other policyholder funds				(446)						248
Other liabilities(c)				301						398
Total liabilities				(5,625)						13,624
Additional paid-in capital				(369)
Retained earnings				1,861						933
Accumulated other comprehensive loss				(524)						(2,197)
Total AIG shareholders’ equity				968						(1,264)
Non-redeemable noncontrolling interests				251
Total equity				1,219						(1,264)
Total liabilities and equity				(4,406)						12,360
Cumulative effect adjustments | Fortitude RE
Assets:
Reinsurance assets, net of allowance for credit losses and disputes				(1,408)						7,666
Cumulative effect adjustments | Excluding Fortitude
Assets:
Reinsurance assets, net of allowance for credit losses and disputes				$ (463)						$ 469

[1] See Note 10 for details of balances associated with variable interest entities.

[2] Updated to reflect the adoption of long-duration targets improvements, see Note 2.