Income Taxes - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Oct. 02, 2016	Sep. 27, 2015	Sep. 28, 2014
Deferred Tax Asset:
State taxes	$ 697	$ 1,746
Reserves and contingent liabilities	2,539	3,842
Allowance for doubtful accounts	3,817	4,115
Accrued liabilities	24,663	19,404
Stock-based compensation	10,684	10,516
Intangibles		2,910
Loss carry-forwards	23,514	5,512
Valuation allowance	(25,447)	(7,791)
Total deferred tax asset	40,467	40,254
Deferred Tax Liability:
Unbilled revenue	(54,638)	(46,513)
Prepaid expense	(2,921)	(5,506)
Intangibles	(33,268)	(33,068)
Property and equipment	(9,358)	(10,713)
Total deferred tax liability	(100,185)	(95,800)
Net deferred tax liability	(59,718)	(55,546)
Undistributed earnings of foreign subsidiaries	65,900
Incremental federal tax due to repatriation of foreign earnings	5,900
Unrecognized tax benefits that would affect the effective tax rate, if recognized	$ 22,800
Period during which unrecognized tax benefits would affect the effective tax rate	12 months
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Beginning balance	$ 21,618	21,717	$ 25,886
Additions for current year tax positions	2,802	1,147	1,243
Additions for prior year tax positions	1,466	2,309	1,416
Reductions for prior year tax positions	(3,100)	(23)
Settlements		(3,532)	(6,828)
Ending balance	22,786	21,618	$ 21,717
Accrued additional interest income	200
Accrued additional interest expense		400
Reduction in accrued interest	0	500
Amount of interest and penalties accrued	1,000	$ 1,200
Foreign
Deferred Tax Liability:
Net operating loss carry forwards which have no expiration date	59,200
Expiration Dates Through 2036 | State
Deferred Tax Liability:
Net operating loss carry forwards which expire at various dates	43,700
Expiration Dates Through 2036 | Foreign
Deferred Tax Liability:
Net operating loss carryforwards	74,200
Net operating loss carry forwards which expire at various dates	$ 15,000