Income taxes - Deferred income taxes (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deferred income tax liabilities:
Investments, including unrealized appreciation	$ 56,766	$ 41,150
Deferred charges reinsurance assumed	1,994	2,073
Property, plant and equipment and equipment held for lease	32,991	32,080
Goodwill and other intangible assets	7,546	7,010
Other	4,452	5,162
Deferred income tax liabilities	103,749	87,475
Deferred income tax assets:
Unpaid losses and loss adjustment expenses	(1,255)	(1,290)
Unearned premiums	(1,285)	(1,196)
Accrued liabilities	(2,626)	(1,790)
Regulatory liabilities	(1,248)	(1,323)
Deferred revenue	(2,282)	(1,880)
Other	(2,709)	(3,579)
Deferred income tax assets	(11,405)	(11,058)
Net deferred income tax liability	$ 92,344	$ 76,417