Commitments and Contingencies: (Details) - USD ($)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Employee Benefit Plan
Service period for vesting of employer contribution	5 years
Company contributions	$ 361,400	$ 319,700	$ 309,800
Operating Leases
Rent expense under operating leases	1,235,000	1,102,000	$ 1,066,500
Minimum rental commitments
2019	503,700
2020	762,500
2021	783,600
2022	784,400
2023	763,300
Thereafter	5,042,900
Total	8,640,400
Total deferred rent	300,000	400,000
Deferred rent included in other liabilities	$ 200,000	$ 200,000