Fair Value Measurement (Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions	$ 7,862		$ 19,570
Payment of contingent consideration	12,100	$ 11,500
Business Combination, Consideration Transferred, Liabilities Incurred	11,100	10,600
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions	7,862	19,497	$ 19,570	$ 13,000
Payment of contingent consideration	12,100	$ 11,500
Fair Value, Inputs, Level 3 [Member] | Accrued Expenses and Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions	$ 7,900