Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Jul. 01, 2018	Dec. 31, 2017	Sep. 30, 2018	Oct. 01, 2017	Oct. 02, 2016	Sep. 27, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective tax rate (as a percent)			21.50%	31.30%	32.60%
Tax at federal statutory rate			24.50%	35.00%	35.00%
Deferred tax benefit from tax reform remeasurement		$ 14,700	$ 14,700
Net deferred tax expense from other non-recurring adjustments			$ 3,600
Effective income tax rate excluding revaluation of deferred taxes (as a percent)			27.90%
Incremental tax expense, disposition of business			$ 2,600
Goodwill written off related to sale of business			12,160
Tax expense (benefit) recognized based on IRS examination and settlement.			$ 1,600	$ (1,200)
Payments made to tax authorities	$ 7,600			$ 21,500
Effective income tax rate excluding excess tax benefit and TCJA impact			25.10%	30.70%
Undistributed earnings of foreign subsidiaries			$ 11,800
Incremental federal tax due to repatriation of foreign earnings			1,000
Valuation allowance			21,479	$ 25,326
Unrecognized tax benefits			$ 9,427	9,337	$ 22,786	$ 21,618
Period during which unrecognized tax benefits would affect the effective tax rate			12 months
Accrued additional interest expense			$ 600	400
Reduction in accrued interest			300	900
Amount of interest and penalties accrued			1,200	1,100
Disposed of by Sale | Non-core field services business
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss on disposition of business	$ 3,400		3,400
State
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net operating loss carry forwards which expire at various dates			43,700
Foreign
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reserve for uncertain tax position in connection with IRS examination				$ 2,300
Net operating loss carry forwards which expire at various dates			31,400
Net operating loss carryforwards			72,400
Net operating loss carry forwards which have no expiration date			$ 41,000