CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($)	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Other comprehensive income (loss):
Change in pension and postretirement benefit costs, income tax expense	$ 81,143	$ 70,938
Change in fair value of marketable securities, tax benefit	2,897	3,471
Change in fair value of interest rate swap and marketable securities, tax benefit	$ 535,029	$ 24,619