FAIR VALUE MEASUREMENTS - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Assets
Gross derivatives	$ 243	$ 271
Netting and credit adjustments	(55)	(28)
Net derivative assets	188	243
Liabilities
Gross derivatives	131	78
Netting and credit adjustments	(54)	(26)
Net derivative liabilities	77	53
Estimated fair value	982	5,706
AerCap
Liabilities
Estimated fair value	982	944
Recurring
Assets
Investment securities with a fair value	38,723	43,706
Netting and credit adjustments	(55)	(28)
Net derivative assets	188	243
Total assets	38,911	43,949
Liabilities
Netting and credit adjustments	(54)	(26)
Net derivative liabilities	77	53
Other	367	311
Total liabilities	444	364
Recurring | Run-off Insurance operations
Assets
Investment securities with a fair value	37,352	37,592
Recurring | Level 1
Assets
Investment securities with a fair value	14	4,767
Gross derivatives	0	0
Total assets	14	4,767
Liabilities
Gross derivatives	0	0
Other	0	0
Total liabilities	0	0
Recurring | Level 2
Assets
Investment securities with a fair value	33,635	32,098
Gross derivatives	243	270
Total assets	33,878	32,368
Liabilities
Gross derivatives	131	78
Other	367	311
Total liabilities	498	389
Recurring | Level 3
Assets
Investment securities with a fair value	5,074	6,841
Gross derivatives	0	0
Total assets	5,074	6,841
Liabilities
Gross derivatives	0	0
Other	0	0
Total liabilities	0	0
Recurring | Level 3 | U.S. corporate
Assets
Investment securities with a fair value	1,627	3,873
Recurring | Level 3 | Mortgage and asset-backed
Assets
Investment securities with a fair value	$ 1,935	$ 1,491