Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020		Mar. 31, 2019
Cash flows from operating activities:
Net earnings (loss)	$ (49,697)		$ 21,732
Adjustments to reconcile net earnings (loss) to operating cash flows:
Investment (gains) losses	68,882		(19,552)
Depreciation and amortization	2,585		2,417
Other	(566)		(469)
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	583		778
Deferred charges reinsurance assumed	260		273
Unearned premiums	2,006		2,054
Receivables and originated loans	(2,083)		(2,237)
Other assets	(1,140)		(990)
Other liabilities	17		(1,800)
Income taxes	(14,049)		5,371
Net cash flows from operating activities	6,798		7,577
Cash flows from investing activities:
Purchases of equity securities	(4,003)		(1,527)
Sales and redemptions of equity securities	2,166		2,063
Purchases of U.S. Treasury Bills and fixed maturity securities	(31,551)		(30,918)
Sales of U.S. Treasury Bills and fixed maturity securities	5,328		2,334
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	3,694		21,114
Purchases of loans and finance receivables	(595)		(14)
Collections of loans and finance receivables	70		93
Acquisitions of businesses, net of cash acquired	(26)		(262)
Purchases of property, plant and equipment and equipment held for lease	(2,968)		(3,151)
Other	81		67
Net cash flows from investing activities	(27,804)		(10,201)
Cash flows from financing activities:
Changes in short term borrowings, net	(1,133)		(503)
Acquisition of treasury stock	(1,741)		(1,585)
Other	(159)		(289)
Net cash flows from financing activities	(346)		(1,678)
Effects of foreign currency exchange rate changes	(184)		15
Increase (decrease) in cash and cash equivalents and restricted cash	(21,536)		(4,287)
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 first quarter *	43,096		26,524
Restricted cash, included in other assets at beginning of year	457		450
Restricted cash, included in other assets at end of first quarter	$ 456		$ 385
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	$ 1,613		$ 1,996
Repayments of borrowings	(1,502)		(2,811)
Cash and cash equivalents at beginning of year	61,151	[1]	27,749
Cash and cash equivalents at end of first quarter	38,717	[1]	22,487
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	4,324		2,945
Repayments of borrowings	(1,748)		(1,431)
Cash and cash equivalents at beginning of year	3,024	[1]	2,612
Cash and cash equivalents at end of first quarter	$ 3,923	[1]	$ 3,652

[1] Cash and cash equivalents included U.S. Treasury Bills with maturities of three months or less when purchased of $19.6 billion at March 31, 2020 and $37.1 billion at December 31, 2019.