COMMITMENTS AND CONTINGENCIES (Details 2) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended		1 Months Ended
	Oct. 31, 2008 subsidiary	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011 Minimum	Dec. 31, 2011 Maximum	Jul. 31, 2011 Infineon Litigation patent	Apr. 30, 2011 Infineon Litigation patent	Aug. 12, 2012 Infineon Litigation patent
Contingencies
Number of patents claimed to be infringed									11
Number of Infineon patents alleged to be either invalid or not infringed									3
Number of Infineon patents Atmel is seeking to declare either invalid or not infringed								11
Number of Atmel patents counterclaimed that Infineon infringed on								6
Number of additional Infineon patents claimed to be infringed by the company								4
Number of patents withdrawn										4
Number of company's French subsidiaries where inspection conducted by European Union Commission	1
Product Warranties
Warranty period of company's products, range (period of time)						30 days	3 years
Activity related to the product warranty liability
Balance at beginning of period		$ 5,665	$ 5,107	$ 5,746	$ 4,019
Accrual for warranties during the period, net of change in estimates		443	1,593	3,066	5,450
Actual costs incurred		(1,146)	(1,355)	(3,850)	(4,124)
Balance at end of period		$ 4,962	$ 5,345	$ 4,962	$ 5,345