Balance Sheet Details (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Sep. 30, 2017
Inventory, Net [Abstract]
Purchased parts and assemblies	$ 139,956		$ 114,285
Work-in-process	188,420		159,784
Finished goods	166,591		140,738
Total inventories	494,967		414,807
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid and refundable income taxes	39,261		28,712
Other taxes receivable	17,967		15,327
Prepaid expenses and other assets	31,262		26,229
Total prepaid expenses and other assets	88,490		70,268
Other Assets, Noncurrent Disclosure [Abstract]
Assets related to deferred compensation arrangements	35,382		31,008
Deferred tax assets	72,616		82,691
Other assets	7,631		12,942
Total other assets	115,629		126,641
Other Liabilities, Current [Abstract]
Accrued payroll and benefits	49,443		72,327
Deferred revenue	22,559		65,237
Warranty reserve	35,912		36,149
Accrued expenses and other	35,348		34,215
Current liabilities held for sale	0		7,021
Customer deposits	15,023		20,052
Total other current liabilities	158,285		235,001
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Beginning balance	36,149	$ 15,949
Additions related to current period sales	41,681	27,854
Warranty costs incurred in the current period	(39,434)	(23,422)
Accruals resulting from acquisitions	179	14,314
Adjustments to accruals related to foreign exchange and other	(2,663)	(712)
Ending balance	35,912	$ 33,983
Other Liabilities, Noncurrent [Abstract]
Long-term taxes payable	54,530		35,866
Deferred compensation	38,898		34,160
Deferred tax liabilities	37,947		45,373
Deferred revenue	5,151		4,765
Asset retirement obligations liability	4,437		5,382
Defined benefit plan liabilities	39,968		39,454
Other long-term liabilities	1,045		1,390
Total other long-term liabilities	$ 181,976		$ 166,390