Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net earnings	$ 4,139	$ 5,657
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(315)	(1,850)
Depreciation and amortization	2,243	2,125
Other	120	228
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	16,900	1,454
Deferred charges reinsurance assumed	(5,783)	(111)
Unearned premiums	1,829	1,476
Receivables and originated loans	(1,197)	(1,987)
Derivative contract assets and liabilities	(460)	810
Income taxes	1,451	497
Other	(622)	(845)
Net cash flows from operating activities	18,305	7,454
Cash flows from investing activities:
Purchases of U.S. Treasury Bills and fixed maturity securities	(45,342)	(14,359)
Purchases of equity securities	(10,590)	(3,059)
Sales of U.S. Treasury Bills and fixed maturity securities	10,048	1,124
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	23,990	3,689
Sales and redemptions of equity securities	3,452	2,258
Purchases of loans and finance receivables	(52)	(175)
Collections of loans and finance receivables	97	80
Acquisitions of businesses, net of cash acquired	(1,599)	(30,185)
Purchases of property, plant and equipment	(2,355)	(2,843)
Other	(115)	(390)
Net cash flows from investing activities	(22,466)	(43,860)
Cash flows from financing activities:
Changes in short term borrowings, net	87	547
Other financing activities	(23)	25
Net cash flows from financing activities	2,015	11,613
Effects of foreign currency exchange rate changes	61	7
Increase (decrease) in cash and cash equivalents	(2,085)	(24,786)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	28,048	67,161
Cash and cash equivalents at end of first quarter	25,963	42,375
Insurance and Other [Member]
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(312)	(1,846)
Cash flows from financing activities:
Proceeds from borrowings	1,203	8,539
Repayments of borrowings	(1,130)	(381)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	23,581	56,612
Cash and cash equivalents at end of first quarter	18,362	37,620
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	2,094
Repayments of borrowings	(446)	(522)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	3,939	3,437
Cash and cash equivalents at end of first quarter	5,584	2,692
Finance and Financial Products [Member]
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(3)	(4)
Cash flows from financing activities:
Proceeds from borrowings	1,298	3,493
Repayments of borrowings	(1,068)	(88)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	528	7,112
Cash and cash equivalents at end of first quarter	$ 2,017	$ 2,063