Income Taxes (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2016	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018	Sep. 30, 2018	Mar. 30, 2019	Oct. 01, 2018	Mar. 31, 2018	Sep. 30, 2017
Income Tax Disclosure [Line Items]
Effective income tax rate		(2940.00%)	(70.00%)	(177.00%)	(39.00%)
Income before income taxes		$ (485)	$ 9,971	$ (13,483)	$ 27,987
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%
Reduction of valuation allowance				$ 1,800
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Percent						24.50%
Operating Loss Carryforwards, Limitations on Use				80.00%
Unrecognized tax benefits		9,700		$ 9,700		$ 9,800
Income tax provision upon recognition of unrecognized tax benefit		9,700		9,700
Unrecognized tax benefits that would impact valuation allowance		3,800		3,800
Potentail reduction in unrecognized tax benefits and accrued interest over next 12 months		(500)		(500)
Stockholders' Equity Attributable to Parent		1,215,595	834,385	1,215,595	834,385	874,589	$ 1,247,708		$ 927,724	$ 885,436
Deferred tax assets		189,371		189,371		165,566
Korea
Income Tax Disclosure [Line Items]
Income tax examination, estimate of possible loss	$ 12,000
US Tax on Undistributed Foreign Earnings [Member]
Income Tax Disclosure [Line Items]
Current Federal, State and Local, Tax Expense (Benefit)					1,700
Net Decrease in Deferred Tax Liability [Member]
Income Tax Disclosure [Line Items]
Deferred Income Tax Expense (Benefit)				14,100
Accounting Standards Update 2016-16
Income Tax Disclosure [Line Items]
Deferred tax assets								$ 75,300
Other Tax Assets								6,000
Other Tax Liabilities								3,000
Accumulated Deficit
Income Tax Disclosure [Line Items]
Stockholders' Equity Attributable to Parent		$ (197,056)	$ (612,600)	$ (197,056)	$ (612,600)	$ (599,409)	$ (182,298)		$ (629,597)	$ (650,840)
Accumulated Deficit | Accounting Standards Update 2016-16
Income Tax Disclosure [Line Items]
Stockholders' Equity Attributable to Parent								$ 72,300