Recent Accounting Pronouncements: (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Sep. 24, 2016
Recently Adopted Accounting Pronouncements
Excess tax benefits on exercised stock options, operating activities		$ 592,800	$ 69,700
Accounting Standards Update 2016-09
Recently Adopted Accounting Pronouncements
Excess tax benefits on exercised stock options, operating activities	$ 74,800	$ 592,800	69,700
Accounting Standards Update 2016-09 | Previously Reported
Recently Adopted Accounting Pronouncements
Excess tax benefits on exercised stock options, financing activities			$ 69,700