Income Taxes: (Details) - USD ($)	12 Months Ended
	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Income Taxes:
Federal statutory tax rate (as a percent)	35.00%
Reconciliation of the expected federal income tax expense based on the federal statutory tax rate to the actual income tax expense
Federal income tax expense at statutory rate (35%)	$ 12,328,700	$ 11,406,100	$ 10,356,500
Change in valuation allowance	(4,400)	(25,800)	7,300
State and local income taxes, net of federal benefit	956,000	897,800	886,200
Permanent differences, including stock option expenses	158,100	144,500	113,000
Other, net	(13,300)	99,700	(4,700)
Total provision for income taxes	13,425,100	12,522,300	11,358,300
Current provision for income taxes:
Federal	13,486,500	10,567,100	10,013,500
State	1,654,800	1,456,400	1,468,600
Foreign	425,900	386,900	375,400
Current provision	15,567,200	12,410,400	11,857,500
Deferred provision for income taxes:
Federal	(1,983,200)	134,200	(449,300)
State	(158,900)	(22,300)	(49,900)
Deferred provision	(2,142,100)	111,900	(499,200)
Total provision for income taxes	13,425,100	12,522,300	11,358,300
Deferred tax assets:
Accounts receivable and lease reserves	345,200	169,600
Accrued restructuring charge		64,200
Non-qualified stock option expense	1,926,400	1,382,400
Deferred franchise and software license fees	810,900	720,900
Trademarks	85,700	91,100
Lease deposits	1,373,000	1,228,300
Loss from and impairment of equity and note investments	4,051,400	4,055,800
Valuation allowance	(4,051,400)	(4,055,800)
Other	372,800	420,100
Total deferred tax assets	4,914,000	4,076,600
Deferred tax liabilities:
Lease revenue and initial direct costs	(8,277,600)	(9,579,400)
Depreciation and amortization	(251,200)	(254,100)
Total deferred tax liabilities	(8,528,800)	(9,833,500)
Total net deferred tax liabilities	(3,614,800)	(5,756,900)
Excess tax benefits related to stock option exercises	26,300	91,100	413,600
Unrecognized tax benefits, including interest and penalties	489,200	465,500
Interest and penalties accrued related to unrecognized tax benefit	19,300	16,500
Activity related to the company's unrecognized tax benefits
Balance at the beginning of the period	449,000	383,700
Increases related to current year tax positions	114,700	136,500
Additions (subtractions) for tax positions of prior years	(8,000)	1,600
Expiration of the statute of limitations for the assessment of taxes	(85,800)	(72,800)
Balance at the end of the period	$ 469,900	$ 449,000	$ 383,700
Period over which various statutes of limitations are expected to expire	12 months