Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details)		9 Months Ended	12 Months Ended
		Jul. 09, 2017 USD ($)	Oct. 01, 2017 USD ($) restaurant	Oct. 02, 2016 USD ($) restaurant	Sep. 27, 2015 USD ($) restaurant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure			$ (60,502,000)	$ (84,698,000)
Asset Impairment Charges			$ 3,096,000	$ 544,000	$ 557,000
Qdoba brand restaurant operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Restaurants | restaurant			726	699	661
Asset Impairment Charges			$ 700,000.0
Jack in the box brand restaurant operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Restaurants | restaurant			2,251	2,255	2,249
Number of Restaurants Closed | restaurant			4
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1]		$ (37,575,000)	$ (36,933,000)
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1]		(22,927,000)	(47,765,000)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1]		0	0
Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[2]		(22,927,000)	(47,765,000)
Interest Rate Swaps [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1],[2]		0	0
Interest Rate Swaps [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1],[2]		(22,927,000)	(47,765,000)
Interest Rate Swaps [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1],[2]		0	0
Non Qualified Deferred Compensation Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[3]		(37,575,000)	(36,933,000)
Non Qualified Deferred Compensation Plan [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1],[3]		(37,575,000)	(36,933,000)
Non Qualified Deferred Compensation Plan [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1],[3]		0	0
Non Qualified Deferred Compensation Plan [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Obligations, Fair Value Disclosure	[1],[3]		$ 0	$ 0
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations [Member] | Jack in the box brand restaurant operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Restaurants Closed | restaurant			9
Gain (Loss) on Sale of Assets and Asset Impairment Charges		$ 4,600,000
UnderperformingQdobaRestaurants [Member] | Qdoba brand restaurant operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Restaurants | restaurant			3
UnderperformingQdobaRestaurants [Member] | Fair Value, Measurements, Nonrecurring [Member] | Qdoba brand restaurant operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of Long-Lived Assets Held-for-use			$ 2,400,000

[1] We did not have any transfers in or out of Level 1, 2 or 3

[2] We entered into interest rate swaps to reduce our exposure to rising interest rates on our variable rate debt. The fair values of our interest rate swaps are based upon Level 2 inputs which include valuation models as reported by our counterparties. The key inputs for the valuation models are quoted market prices, discount rates and forward yield curves.

[3] We maintain an unfunded defined contribution plan for key executives and other members of management. The fair value of this obligation is based on the closing market prices of the participants’ elected investments.