Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Revenues:
System and software	$ 681,881	$ 631,549	$ 562,355
Service and support	406,846	383,089	352,398
Total revenues	1,088,727	1,014,638	914,753
Cost of revenues:
System and software	64,280	54,972	42,865
Service and support	117,609	108,690	99,612
Amortization of purchased technology	7,801	9,796	13,771
Total cost of revenues	189,690	173,458	156,248
Gross profit	899,037	841,180	758,505
Operating expenses:
Research and development	313,962	310,758	296,631
Marketing and selling	338,653	326,608	312,834
General and administration	74,324	74,811	80,948
Equity in earnings of Frontline	(1,764)	(2,268)	(2,051)
Amortization of intangible assets	5,915	5,905	7,347
Special charges	6,314	13,174	10,257
Total operating expenses	737,404	728,988	705,966
Operating income	161,633	112,192	52,539
Other (expense) income, net	(1,432)	1,576	(2,116)
Interest expense	(18,866)	(31,444)	(18,411)
Income before income tax	141,335	82,324	32,012
Income tax expense (benefit)	2,701	(1,063)	3,428
Net income	138,634	83,387	28,584
Less: Loss attributable to noncontrolling interest	(102)	(485)	0
Net income attributable to Mentor Graphics shareholders	$ 138,736	$ 83,872	$ 28,584
Net income per share:
Basic (in dollars per share)	$ 1.20	$ 0.76	$ 0.27
Diluted (in dollars per share)	$ 1.17	$ 0.74	$ 0.26
Weighted average number of shares outstanding:
Basic (in shares)	110,998	110,138	107,743
Diluted (in shares)	114,017	112,915	109,861