Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019		Sep. 30, 2018
Cash flows from operating activities:
Net earnings (loss)	$ 52,562		$ 29,713
Adjustments to reconcile net earnings (loss) to operating cash flows:
Investment (gains) losses	(40,079)		(12,750)
Depreciation and amortization	7,407		7,169
Other	(1,740)		(677)
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	3,252		2,272
Deferred charges reinsurance assumed	745		827
Unearned premiums	2,663		2,974
Receivables and originated loans	(3,618)		(4,781)
Other assets	(2,419)		(1,788)
Other liabilities	(889)		805
Income taxes	8,726		2,791
Net cash flows from operating activities	26,610		26,555
Cash flows from investing activities:
Purchases of U.S. Treasury Bills and fixed maturity securities	(72,189)		(85,502)
Purchases of equity securities	(15,090)		(38,552)
Sales of U.S. Treasury Bills and fixed maturity securities	13,602		26,903
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	94,742		83,742
Sales and redemptions of equity securities	7,127		14,164
Purchases of loans and finance receivables	(57)		(1,748)
Collections of loans and finance receivables	259		266
Acquisitions of businesses, net of cash acquired	(732)		(521)
Purchases of property, plant and equipment and equipment held for lease	(11,139)		(10,040)
Other	(1,067)		257
Net cash flows from investing activities	15,456		(11,031)
Cash flows from financing activities:
Changes in short term borrowings, net	165		(2,754)
Acquisition of treasury stock	(2,807)		(928)
Other	(341)		(277)
Net cash flows from financing activities	2,509		(5,526)
Effects of foreign currency exchange rate changes	(95)		(109)
Increase in cash and cash equivalents and restricted cash	44,480		9,889
Cash and cash equivalents and restricted cash at beginning of year	30,811		32,212
Cash and cash equivalents and restricted cash at end of third quarter	75,291		42,101
Restricted cash, included in other assets at beginning of year	450		629
Restricted cash, included in other assets at end of third quarter	$ 515		$ 663
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	$ 8,141		$ 2,394
Repayments of borrowings	(5,046)		(7,322)
Cash and cash equivalents at beginning of year	27,749	[1]	28,673
Cash and cash equivalents at end of third quarter	71,064	[1]	38,141
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	4,163		7,019
Repayments of borrowings	(1,766)		(3,658)
Cash and cash equivalents at beginning of year	2,612	[1]	2,910
Cash and cash equivalents at end of third quarter	$ 3,712	[1]	$ 3,297

[1] Cash and cash equivalents included U.S. Treasury Bills with maturities of three months or less when purchased of $40.6 billion at September 30, 2019 and $3.9 billion at December 31, 2018.