Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net earnings (loss)	$ (1,071)	$ 4,139
Adjustments to reconcile net earnings (loss) to operating cash flows:
Investment gains/losses	7,809	(315)
Depreciation and amortization	2,387	2,243
Other	(1)	120
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	69	16,900
Deferred charges reinsurance assumed	271	(5,783)
Unearned premiums	2,352	1,829
Receivables and originated loans	(2,186)	(1,197)
Other assets	(881)	(339)
Other liabilities	(392)	(753)
Income taxes	(801)	1,451
Net cash flows from operating activities	7,556	18,295
Cash flows from investing activities:
Purchases of U.S. Treasury Bills and fixed maturity securities	(13,037)	(45,342)
Purchases of equity securities	(14,765)	(10,590)
Sales of U.S. Treasury Bills and fixed maturity securities	13,577	10,048
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	35,088	23,990
Sales and redemptions of equity securities	4,240	3,452
Purchases of loans and finance receivables	(41)	(52)
Collections of loans and finance receivables	100	97
Acquisitions of businesses, net of cash acquired	(112)	(1,599)
Purchases of property, plant and equipment	(2,589)	(2,355)
Other	(153)	(181)
Net cash flows from investing activities	22,308	(22,532)
Cash flows from financing activities:
Changes in short term borrowings, net	(1,929)	87
Other	(102)	(23)
Net cash flows from financing activities	(3,794)	2,015
Effects of foreign currency exchange rate changes	92	61
Increase (decrease) in cash and cash equivalents and restricted cash	26,162	(2,161)
Cash and cash equivalents and restricted cash:
Cash and cash equivalents and restricted cash at beginning of year	32,212	28,643
Cash and cash equivalents and restricted cash at end of first quarter	58,374	26,482
Restricted cash, included in other assets at beginning of year	629	595
Restricted cash, included in other assets at end of first quarter	493	519
Insurance and Other [Member]
Cash flows from financing activities:
Proceeds from borrowings	17	1,203
Repayments of borrowings	(1,840)	(1,130)
Cash and cash equivalents and restricted cash:
Cash and cash equivalents at beginning of year	25,460	23,581
Cash and cash equivalents at end of first quarter	50,559	18,362
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	3,613	2,094
Repayments of borrowings	(1,221)	(446)
Cash and cash equivalents and restricted cash:
Cash and cash equivalents at beginning of year	2,910	3,939
Cash and cash equivalents at end of first quarter	3,550	5,584
Finance and Financial Products [Member]
Cash flows from financing activities:
Proceeds from borrowings	20	1,298
Repayments of borrowings	(2,352)	(1,068)
Cash and cash equivalents and restricted cash:
Cash and cash equivalents at beginning of year	3,213	528
Cash and cash equivalents at end of first quarter	$ 3,772	$ 2,017