CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($)	3 Months Ended
Mar. 30, 2019	Mar. 31, 2018
Other comprehensive income (loss):
Change in pension and postretirement benefit costs, tax (expense)	$ (70,938)	$ (65,557)
Change in fair value of marketable securities, tax benefit	3,471	0
Change in fair value of interest rate swap and marketable securities, tax benefit (expense)	$ 24,619	$ (65,557)

Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount of tax expense (benefit), after reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

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