Acquisition Acquisition (Details) (USD $)	12 Months Ended								3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Feb. 18, 2011	Sep. 30, 2011 Kingstone Holding Company	Feb. 18, 2011 Kingstone Holding Company	Feb. 18, 2011 Kingstone Semiconductor Company Ltd	Feb. 18, 2011 Silicon Jade Limited [Member]	Sep. 30, 2011 Common Stock Silicon Jade Limited [Member]	Mar. 31, 2011 Common Stock Silicon Jade Limited [Member]	Feb. 18, 2011 Common Stock Silicon Jade Limited [Member]	Feb. 18, 2011 In-process research and development Kingstone Holding Company	Feb. 18, 2011 Non-compete agreements Kingstone Holding Company	Feb. 18, 2011 Developed Technology Rights [Member] Kingstone Holding Company
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired						55.00%
Business Acquisition, Percentage of Voting Interests Acquired of Acquiree Owned Subsidiary							100.00%
Business Acquisition, Cost of Acquired Entity, Purchase Price				$ 9,300,000		$ 4,000,000		$ 5,300,000
Business Acquisition, Cost of Acquired Entity, Cash Paid						300,000		1,400,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares										153,090
Business Acquisition Equity Interest Issued Or Issuable Value Assigned According With Purchase Agreement											4,100,000
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned											3,800,000
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred						3,700,000
Business Acquisition Loan Provided To Acquiree						4,000,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount						8,500,000
Acquired Finite-lived Intangible Asset, Amount						3,200,000						1,600,000	900,000	700,000
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value						6,800,000
Business Acquisition Percentage of Voting Interest Acquired Discounted						10.00%
Business Acquisition, Cost of Acquired Entity, Transaction Costs					900,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased									153,090
Stock Repurchase Cash Paid									4,100,000
Treasury Stock Acquired, Average Cost Per Share									$ 8.00
Treasury Stock, Value									1,200,000
Expense related to reacquired shares	$ 0	$ 2,855,000	$ 0						$ 2,900,000