Balance Sheet Details (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Sep. 30, 2017
Inventory, Net [Abstract]
Purchased parts and assemblies	$ 124,544		$ 114,285
Work-in-process	159,280		159,784
Finished goods	148,985		140,738
Total inventories	432,809		414,807
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid and refundable income taxes	27,606		28,712
Other taxes receivable	16,865		15,327
Prepaid expenses and other assets	32,532		26,229
Total prepaid expenses and other assets	77,003		70,268
Other Assets, Noncurrent Disclosure [Abstract]
Assets related to deferred compensation arrangements	33,930		31,008
Deferred tax assets	86,831		82,691
Other assets	6,955		12,942
Total other assets	127,716		126,641
Other Liabilities, Current [Abstract]
Accrued payroll and benefits	55,697		72,327
Deferred revenue	44,709		65,237
Warranty reserve	37,809		36,149
Accrued expenses and other	31,699		34,215
Current liabilities held for sale (See Note 18)	735		7,021
Customer deposits	20,191		20,052
Total other current liabilities	190,840		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	14,140	8,814
Warranty costs incurred in the current period	(12,404)	(6,399)
Accruals resulting from acquisitions	0	12,593
Adjustments to accruals related to foreign exchange and other	(76)	(2,357)
Ending balance	37,809	$ 28,600
Other Liabilities, Noncurrent [Abstract]
Long-term taxes payable	54,779		35,866
Deferred compensation	37,291		34,160
Deferred tax liabilities	42,457		45,373
Deferred revenue	4,400		4,765
Asset retirement obligations liability	4,779		5,382
Defined benefit plan liabilities	40,157		39,454
Other long-term liabilities	1,209		1,390
Total other long-term liabilities	$ 185,072		$ 166,390