Acquisition of Chingis (Narrative) (Details) (USD $)	3 Months Ended												12 Months Ended			1 Months Ended	0 Months Ended				12 Months Ended
	Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	May 31, 2013 Chingis	Sep. 30, 2012 Chingis	Sep. 14, 2012 Chingis	Sep. 30, 2013 Chingis	Sep. 30, 2013 Chingis Selling, general and administrative	Sep. 30, 2013 Developed technology Chingis	Sep. 30, 2013 Customer relationships Chingis	Sep. 30, 2013 Other intangibles Chingis
Business Acquisition [Line Items]
Investment in consolidated subsidiaries, net of cash and cash equivalents acquired													$ 0	$ 13,210,000	$ 15,960,000			$ 13,200,000
Cash on acquired entity's balance sheet																		18,600,000
Estimated useful lives of purchased definite lived intangible assets																					6 years	6 years	3 years
Costs related to acquisition																				400,000
Revenue																	1,200,000
Net loss	(4,730,000)	[1]	(7,246,000)	[2]	(3,280,000)	[3]	(2,488,000)	13,118,000	[4]	(3,147,000)	(3,597,000)	(3,769,000)	(17,744,000)	2,605,000	(56,123,000)		1,200,000
Business Acquisition, Additional Percentage Of Voting Interests Acquired																4.80%
Payments to Acquire Additional Interest in Subsidiaries													1,614,000	2,370,000	0	1,600,000
Percentage of equity acquired																		94.10%
Total purchase price																		$ 31,800,000
Noncontrolling Interest, Ownership Percentage by Parent																			98.90%

[1] In the September 2013 quarter, the Company realized a gain of $2.9 million from the sale of a portion of its Nanya shares.

[2] In the June 2013 quarter, the Company realized a gain from the sale of investments of $7.3 million including $7.0 million from the sale of a portion of its Nanya shares.

[3] In the March 2013 quarter, the Company realized a gain of $2.1 million from the sale of a portion of its Nanya shares.

[4] In the September 2012 quarter, the Company recorded a charge of approximately $14.3 million for the impairment of certain tangible and intangible assets related to the acquisition of Si En and a charge of approximately $2.3 million to write-down its investment in SMIC due to the decline in fair market value being considered other than temporary.