Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net earnings	$ 45,353	$ 24,427	$ 24,414
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(1,410)	(7,553)	(9,373)
Depreciation and amortization	9,188	8,901	7,779
Other	458	(161)	751
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	25,027	4,372	2,262
Deferred charges reinsurance assumed	(7,231)	(360)	84
Unearned premiums	1,761	968	1,392
Receivables and originated loans	(1,990)	(3,302)	(1,650)
Derivative contract assets and liabilities	(775)	(946)	(974)
Income taxes	(24,957)	4,044	5,718
Other	352	2,145	1,088
Net cash flows from operating activities	45,776	32,535	31,491
Cash flows from investing activities:
Purchases of U.S. Treasury Bills and fixed maturity securities	(158,492)	(96,568)	(17,891)
Purchases of equity securities	(20,326)	(16,508)	(10,220)
Purchase of Kraft Heinz common stock			(5,258)
Sales of U.S. Treasury Bills and fixed maturity securities	49,327	18,757	2,471
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	86,727	26,177	14,656
Sales and redemptions of equity securities	19,512	28,464	8,747
Purchases of loans and finance receivables	(1,435)	(307)	(179)
Collections of loans and finance receivables	1,702	490	492
Acquisitions of businesses, net of cash acquired	(2,708)	(31,399)	(4,902)
Purchases of property, plant and equipment	(11,708)	(12,954)	(16,082)
Other	(3,690)	(419)	165
Net cash flows from investing activities	(41,091)	(84,267)	(28,001)
Cash flows from financing activities:
Changes in short term borrowings, net	2,079	130	(378)
Other	(121)	112	(233)
Net cash flows from financing activities	(1,398)	12,791	3,803
Effects of foreign currency exchange rate changes	248	(172)	(165)
Increase (decrease) in cash and cash equivalents	3,535	(39,113)	7,128
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	28,048	67,161	60,033
Cash and cash equivalents at end of year	31,583	28,048	67,161
Insurance and Other [Member]
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(1,202)	(5,128)	(9,363)
Cash flows from financing activities:
Proceeds from borrowings	1,342	9,431	3,358
Repayments of borrowings	(1,856)	(1,264)	(1,916)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	23,581	56,612
Cash and cash equivalents at end of year	25,460	23,581	56,612
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	3,013	3,077	5,479
Repayments of borrowings	(3,549)	(2,123)	(1,725)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	3,939	3,437
Cash and cash equivalents at end of year	2,910	3,939	3,437
Finance and Financial Products [Member]
Adjustments to reconcile net earnings to operating cash flows:
Investment gains/losses	(208)	(2,425)	(10)
Cash flows from financing activities:
Proceeds from borrowings	1,303	4,741	1,045
Repayments of borrowings	(3,609)	(1,313)	(1,827)
Cash and cash equivalents:
Cash and cash equivalents at beginning of year	528	7,112
Cash and cash equivalents at end of year	$ 3,213	$ 528	$ 7,112