Income Taxes (Summary Of Federal Income Tax Rate And Effective Income Tax Rate) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jan. 03, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount		$ (492)	$ (23,517)	$ 9,284
Statutory federal income tax rate		(35.00%)	(35.00%)	35.00%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		$ 17,334	$ 37,996	$ 16,718
Change in valuation allowance		1233.00%	57.00%	63.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount		$ 627	$ (82)	$ 1,788
State income taxes, net of federal tax benefit		45.00%	0.00%	7.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount	$ (2,100)	$ (2,182)	$ (5,981)	$ (2,097)
Federal and state research and development credits		(155.00%)	(9.00%)	(8.00%)
Effective Income Tax Rate Reconciliation, Resolution of Uncertain Tax Positions, Amount		$ (3,840)	$ 0	$ (2,991)
Effective Income Tax Rate Reconciliation, Resolution of Uncertain Tax Positions, Percent		(273.00%)	0.00%	(11.00%)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount		$ (27,932)	$ (27,513)	$ (56,375)
Foreign rate differences		(1987.00%)	(41.00%)	(213.00%)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Withholding, Amount		$ 2,737	$ 1,987	$ 3,764
Foreign withholding tax		195.00%	3.00%	14.00%
Effective Income Tax Rate Reconciliation, Permanent Domestic Items, Amount		$ 6,030	$ 2,886	$ 9,062
U.S. permanent items		429.00%	4.00%	34.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount		$ 73	$ 1,497	$ (185)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		4.00%	2.00%	0.00%
Benefit from income taxes		$ (7,645)	$ (12,727)	$ (21,032)
Effective income tax rate		(544.00%)	(19.00%)	(79.00%)