COMMITMENTS AND CONTINGENCIES (Details 2) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		12 Months Ended		1 Months Ended
	Oct. 31, 2008 Subsidiary	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011 Minimum	Dec. 31, 2011 Maximum	Jul. 31, 2011 Infineon Litigation patent	Apr. 30, 2011 Infineon Litigation patent
Contingencies
Number of patents claimed to be infringed							11
Number of Infineon patents Atmel is seeking to declare either invalid or not infringed						11
Number of Infineon patents alleged to be either invalid or not infringed							3
Number of Atmel patents counterclaimed that Infineon infringed on						6
Number of additional Infineon patents claimed to be infringed by the company						4
Product Warranties
Warranty period of company's products, range (period of time)				30 days	2 years
Activity related to the product warranty liability
Balance at beginning of period		$ 5,746	$ 4,019
Accrual for warranties during the period, net of change in estimates		1,287	2,204
Actual costs incurred		(1,309)	(1,315)
Balance at end of period		$ 5,724	$ 4,908
Number of company's French subsidiaries where inspection conducted by European Union Commission (the "Commission")	1