Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Apr. 30, 2012	Apr. 30, 2011
Revenues:
System and software	$ 149,356	$ 139,645
Service and support	98,562	90,390
Total revenues	247,918	230,035
Cost of revenues:
System and software	14,790	16,077
Service and support	28,414	25,211
Amortization of purchased technology	2,179	3,357
Total cost of revenues	45,383	44,645
Gross margin	202,535	185,390
Operating expenses:
Research and development	71,046	69,368
Marketing and selling	79,752	77,924
General and administration	16,649	16,785
Equity in earnings of Frontline	(587)	(1,017)
Amortization of intangible assets	1,706	1,610
Special charges	1,147	4,547
Total operating expenses	169,713	169,217
Operating income	32,822	16,173
Other income (expense), net	83	(475)
Interest expense	(4,594)	(17,440)
Income (loss) before income tax	28,311	(1,742)
Income tax expense	781	611
Net income (loss)	27,530	(2,353)
Less: Loss attributable to noncontrolling interest	(652)	0
Net income (loss) attributable to Mentor Graphics shareholders	$ 28,182	$ (2,353)
Net income (loss) per share:
Basic (in dollars per share)	$ 0.26	$ (0.02)
Diluted (in dollars per share)	$ 0.25	$ (0.02)
Weighted average number of shares outstanding:
Basic (in shares)	109,907	111,769
Diluted (in shares)	113,243	111,769