Income Taxes (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2012	Apr. 02, 2011	Mar. 31, 2012	Apr. 02, 2011	Sep. 30, 2011	Jan. 01, 2011
Income Tax Disclosure [Line Items]
Effective income tax rate	9.00%	19.00%	24.00%	16.00%
Income before income taxes	$ 3,900,000	$ 23,400,000	$ 33,800,000	$ 38,600,000
Statutory Federal income tax rate	35.00%	35.00%
Noncash charge related to Japanese legislative change and expiration of U.S. R&D tax credit	1,500,000
Tax benefit related to retroactive extension of R&D tax credit		1,800,000
Unrecognized tax benefit	17,400,000		17,400,000		16,200,000
Unrecognized tax benefits, net of state tax benefits	17,000,000				15,900,000
Income tax provision upon recognition of unrecognized tax benefit	16,300,000		16,300,000
Income tax interest expense		100,000	100,000	200,000
Income tax penalty	0	0
Income tax accrued interest	2,100,000		2,100,000		2,000,000
Income tax accrued penalty	0		0			0
Maximum amount of decrease in unrecognized tax benefits	7,000,000		7,000,000
Payment From Foreign Subsidiary [Member]
Income Tax Disclosure [Line Items]
Potential tax benefit from not receiving research and development cost sharing prepayment from foreign subsidiary	$ 7,500,000		$ 7,500,000