Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net earnings	$ 8,494	$ 10,739
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(605)	(2,493)
Depreciation and amortization	4,539	4,359
Other	403	(119)
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	18,075	1,769
Deferred charges reinsurance assumed	(5,550)	35
Unearned premiums	1,830	1,444
Receivables and originated loans	(1,608)	(2,716)
Derivative contract assets and liabilities	(395)	790
Income taxes	1,893	1,822
Other	(449)	(366)
Net cash flows from operating activities	26,627	15,264
Cash flows from investing activities:
Purchases of U.S. Treasury Bills and fixed maturity securities	(68,547)	(33,029)
Purchases of equity securities	(13,628)	(4,129)
Sales of U.S. Treasury Bills and fixed maturity securities	20,164	2,625
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	34,164	8,828
Sales and redemptions of equity securities	7,815	12,444
Purchases of loans and finance receivables	(1,350)	(188)
Collections of loans and finance receivables	393	174
Acquisitions of businesses, net of cash acquired	(1,721)	(30,440)
Purchases of property, plant and equipment	(5,149)	(6,144)
Other	(112)	(397)
Net cash flows from investing activities	(27,971)	(50,256)
Cash flows from financing activities:
Changes in short term borrowings, net	462	618
Other financing activities	(92)	(46)
Net cash flows from financing activities	(469)	11,753
Effects of foreign currency exchange rate changes	183	2
Increase in cash and cash equivalents	(1,630)	(23,237)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	28,048	67,161
Cash and cash equivalents at June 30	26,418	43,924
Insurance and Other [Member]
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(599)	(2,486)
Cash flows from financing activities:
Proceeds from borrowings	1,295	8,600
Repayments of borrowings	(1,180)	(1,148)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	23,581	56,612
Cash and cash equivalents at June 30	20,142	33,033
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	2,413	2,211
Repayments of borrowings	(1,768)	(1,781)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	3,939	3,437
Cash and cash equivalents at June 30	4,962	3,036
Finance and Financial Products [Member]
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(6)	(7)
Cash flows from financing activities:
Proceeds from borrowings	1,298	3,494
Repayments of borrowings	(2,897)	(195)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	528	7,112
Cash and cash equivalents at June 30	$ 1,314	$ 7,855