CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Statement of Comprehensive Income [Abstract]
Net earnings	$ 680,271	$ 555,271
Other comprehensive earnings:
Unrealized (loss) on debt securities net of income taxes of $(8,175) in 2018. Unrealized gain on debt and equity securities net of income taxes of $24,507 in 2017.	(23,981)	38,918
Reclassification adjustment for net realized loss on debt securities net of income taxes of $8 in 2018. Reclassification adjustment for net realized (gain) on debt and equity securities net of income taxes of $(12,082) in 2017.	22	(19,187)
Adjustment to postretirement benefit obligation net of income taxes of $193 in 2018.	565	0
Comprehensive earnings	$ 656,877	$ 575,002