Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent of match	75.00%	75.00%	75.00%
Employer matching pre-tax and Roth 401(k) contribution, percent	6.00%	6.00%	6.00%
Employer matching contributions	$ 5,370	$ 5,394	$ 5,483
Pretax amount recognized in other comprehensive income	542
Portion of accumulated comprehensive income recognized as component of net periodic benefit cost over the next fiscal year	1,201
Actuarial gain (loss)	$ (8,304)	$ (871)
Discount rate	0.72%	1.89%
Discount rate calculation assumption, description	The discount rate is calculated based on zero-coupon bond yields published by the Deutsche Bundesbank for maturities that match the weighted average duration of the pension liability, adjusted for the average credit spread of corporate bond rates above the government bond yields.
Accumulated benefit obligation of the defined benefit retirement plan	$ 37,182	$ 31,077
Aggregate liabilities associated with other postretirement plans	$ 3,412	$ 3,924
Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Employee benefit plan target allocations	50.00%
Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Employee benefit plan target allocations	50.00%

Other Postretirement Plans Liabilities Current And Noncurrent

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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount, before tax, after reclassification adjustment, of increase (decrease) in accumulated other comprehensive income from gain (loss) of defined benefit plan.

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Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

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Description of assumption used to determine benefit obligation and net periodic benefit cost of defined benefit plan. Includes, but is not limited to, discount rate, rate of compensation increase, expected long-term rate of return on plan assets and interest crediting rate.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position.

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Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

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Amount of cost for defined contribution plan.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Percentage employer matches of the employee's percentage contribution matched.

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