Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019
Cash flows from operating activities:
Net earnings	$ 7,123		$ 52,562
Adjustments to reconcile net earnings to operating cash flows:
Investment (gains) losses	(2,032)		(40,079)
Depreciation and amortization	7,692		7,407
Other, including asset impairment charges	10,934		(1,740)
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	4,480		3,252
Deferred charges reinsurance assumed	735		745
Unearned premiums	2,544		2,663
Receivables and originated loans	(3,223)		(3,618)
Other assets	(1,673)		(2,419)
Other liabilities	2,446		(889)
Income taxes	201		8,726
Net cash flows from operating activities	29,227		26,610
Cash flows from investing activities:
Purchases of equity securities	(22,406)		(15,090)
Sales of equity securities	28,564		7,127
Purchases of U.S. Treasury Bills and fixed maturity securities	(153,897)		(72,189)
Sales of U.S. Treasury Bills and fixed maturity securities	23,744		13,602
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	81,252		94,742
Purchases of loans and finance receivables	(619)		(57)
Collections of loans and finance receivables	268		259
Acquisitions of businesses, net of cash acquired	(111)		(732)
Purchases of property, plant and equipment and equipment held for lease	(9,516)		(11,139)
Other	(1,685)		(1,067)
Net cash flows from investing activities	(54,406)		15,456
Cash flows from financing activities:
Changes in short term borrowings, net	(1,062)		165
Acquisition of treasury stock	(15,712)		(2,807)
Other	(196)		(341)
Net cash flows from financing activities	(11,676)		2,509
Effects of foreign currency exchange rate changes	(340)		(95)
Increase (decrease) in cash and cash equivalents and restricted cash	(37,195)		44,480
Cash and cash equivalents and restricted cash at beginning of year	64,632		30,811
Cash and cash equivalents and restricted cash at end of third quarter *	27,437		75,291
Restricted cash, included in other assets at beginning of year	457		450
Restricted cash, included in other assets at end of third quarter	$ 620		$ 515
Restricted Cash and Cash Equivalents, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsMember		us-gaap:OtherAssetsMember
Insurance and Other [Member]
Cash flows from financing activities:
Proceeds from borrowings	$ 3,435		$ 8,141
Repayments of borrowings	(2,116)		(5,046)
Cash and cash equivalents at beginning of year	61,151	[1]	27,749
Cash and cash equivalents at end of third quarter	23,078	[1]	71,064
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	6,424		4,163
Repayments of borrowings	(2,449)		(1,766)
Cash and cash equivalents at beginning of year	3,024	[1]	2,612
Cash and cash equivalents at end of third quarter	$ 3,739	[1]	$ 3,712

[1] Cash and cash equivalents includes U.S. Treasury Bills with maturities of three months or less when purchased of $2.4 billion at September 30, 2020 and $37.1 billion at December 31, 2019.