Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 154,866	$ 94,176	$ 145,177
Other comprehensive loss, net of tax:
Change in accumulated translation adjustment	(4,448)	(8,947)	(30,360)
Change in unrealized gain (loss) on derivative instruments	16	(78)	0
Change in pension liability	(33)	(166)	(285)
Other comprehensive loss	(4,465)	(9,191)	(30,645)
Comprehensive income	150,401	84,985	114,532
Net loss	0	(2,101)	(1,962)
Change in accumulated translation adjustment	0	22	45
Comprehensive loss attributable to the noncontrolling interest	0	(2,079)	(1,917)
Comprehensive income attributable to Mentor Graphics shareholders	$ 150,401	$ 87,064	$ 116,449