Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net earnings	$ 406,980	$ 677,744	$ 616,172	$ 680,271	$ 766,624	$ 474,927	$ 495,072	$ 555,271	$ 2,381,167	$ 2,291,894	$ 2,025,688
Other comprehensive earnings:
Unrealized (loss) on debt securities net of income taxes of $(6,521) in 2018. Unrealized gain on debt and equity securities net of income taxes of $110,818 and $11,093 in 2017 and 2016, respectively.									(19,126)	175,978	17,615
Reclassification adjustment for net realized loss on debt securities net of income taxes of $118 in 2018. Reclassification adjustment for net realized (gain) on debt and equity securities net of income taxes of $(42,088) and $(12,464) in 2017 and 2016, respectively.									346	(66,836)	(19,792)
Adjustment to postretirement benefit obligation net of income taxes of $2,963, $(4,406) and $(418) in 2018, 2017 and 2016, respectively.									8,692	(6,997)	(664)
Comprehensive earnings									$ 2,371,079	$ 2,394,039	$ 2,022,847