Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net sales									$ 7,126	$ 6,840	$ 6,583
Cost of sales	$ 1,768	$ 1,517	$ 1,719	$ 1,548	$ 1,634	$ 1,591	$ 1,676	$ 1,493	6,552	6,394	6,033
Operating income (loss)	134	39	9	63	89	(8)	63	(34)	245	110	236
Other investment income (loss)									84	225	(152)
Net earnings (loss) attributable to Seaboard	$ 259	$ 154	$ (27)	$ (103)	$ 173	$ (8)	$ 65	$ 57	$ 283	$ 287	$ 3
Earnings per common share	$ 222.52	$ 132.58	$ (23.51)	$ (88.73)	$ 148.75	$ (7.23)	$ 56.26	$ 48.88	$ 244.21	$ 246.62	$ 2.26
As Previously Reported
Net sales	$ 1,990	$ 1,645	$ 1,808	$ 1,683	$ 1,812	$ 1,663	$ 1,822	$ 1,543
Cost of sales	1,768	1,527	1,717	1,548	1,632	1,589	1,686	1,493		$ 6,400	$ 6,060
Operating income (loss)	134	29	11	63	91	(6)	53	(34)		$ 104	$ 209
Other investment income (loss)	125	56	128	(225)	73	2	37	113
Net earnings (loss) attributable to Seaboard	$ 259	$ 147	$ (26)	$ (103)	$ 175	$ (7)	$ 58	$ 57
Earnings per common share	$ 222.52	$ 126.17	$ (22.35)	$ (88.43)	$ 149.91	$ (6.00)	$ 50.13	$ 48.79		$ 242.78	$ (14.61)
Impact of Accounting Change
Cost of sales		$ (10)	$ 2		$ 2	$ 2	$ (10)
Operating income (loss)		10	(2)		(2)	(2)	10
Net earnings (loss) attributable to Seaboard		$ 7	$ (1)		$ (2)	$ (1)	$ 7
Earnings per common share		$ 6.41	$ (1.16)	$ (0.30)	$ (1.16)	$ (1.23)	$ 6.13	$ 0.09