Consolidated Statement of Stockholders Equity (USD $) In Thousands	Total USD ($)	Common Stock	Additional Paid-in Capital USD ($)	Retained Earnings USD ($)	Accumulated Other Comprehensive Income (Loss) USD ($)	Stockholders' Equity, Total USD ($)	Noncontrolling Interest USD ($)
Stockholders' equity at Jan. 31, 2011			$ 765,179	$ (20,158)	$ 31,693	$ 776,714
Common stock, shares outstanding at Jan. 31, 2011		111,249
Net income attributable to Mentor Graphics shareholders	83,872			83,872		83,872
Net income (loss) attributable to noncontrolling interest	(485)						(485)
Other comprehensive loss					(3,013)	(3,013)
Change in accumulated translation adjustment attributable to noncontrolling interest	(127)						(127)
Convertible debt feature			42,531			42,531
Acquisition of controlling interest			(815)			(815)	8,196
Adjustment of noncontrolling interest to redemption value				(1,682)		(1,682)	1,682
Stock issued under stock awards and stock purchase plans, shares		4,945
Stock issued under stock awards and stock purchase plans, amount			37,460			37,460
Stock repurchased, shares		(6,805)
Stock repurchased, amount			(89,996)			(89,996)
Stock compensation expense			21,516			21,516
Stock withheld for taxes, shares		(43)
Stock withheld for taxes, amount			(513)			(513)
Noncontrolling interest with redemption feature							9,266
Stockholders' equity at Jan. 31, 2012			775,362	62,032	28,680	866,074
Common stock, shares outstanding at Jan. 31, 2012		109,346
Net income attributable to Mentor Graphics shareholders	138,736			138,736		138,736
Net income (loss) attributable to noncontrolling interest	(102)						(102)
Other comprehensive loss					(3,281)	(3,281)
Change in accumulated translation adjustment attributable to noncontrolling interest	(56)						(56)
Adjustment of noncontrolling interest to redemption value				(3,590)		(3,590)	3,590
Stock issued under stock awards and stock purchase plans, shares		5,875
Stock issued under stock awards and stock purchase plans, amount			46,756			46,756
Stock repurchased, shares		(2,245)
Stock repurchased, amount			(33,914)			(33,914)
Stock compensation expense			23,697			23,697
Stock withheld for taxes, shares		(74)
Stock withheld for taxes, amount			(1,265)			(1,265)
Tax benefit associated with the exercise of stock options			266			266
Noncontrolling interest with redemption feature	12,698						12,698
Stockholders' equity at Jan. 31, 2013			810,902	197,178	25,399	1,033,479
Common stock, shares outstanding at Jan. 31, 2013	112,902	112,902
Net income attributable to Mentor Graphics shareholders	155,258			155,258		155,258
Net income (loss) attributable to noncontrolling interest	(1,700)						(1,700)
Other comprehensive loss					(6,596)	(6,596)
Change in accumulated translation adjustment attributable to noncontrolling interest	(5)						(5)
Adjustment of noncontrolling interest to redemption value				(4,486)		(4,486)	4,486
Dividends				(20,398)		(20,398)
Stock issued under stock awards and stock purchase plans, shares		5,618
Stock issued under stock awards and stock purchase plans, amount			53,013			53,013
Stock repurchased, shares		(2,593)
Stock repurchased, amount			(49,995)			(49,995)
Stock compensation expense			29,350			29,350
Stock withheld for taxes, shares		(205)
Stock withheld for taxes, amount			(4,717)			(4,717)
Tax benefit associated with the exercise of stock options			386			386
Noncontrolling interest with redemption feature	15,479						15,479
Stockholders' equity at Jan. 31, 2014			$ 838,939	$ 327,552	$ 18,803	$ 1,185,294
Common stock, shares outstanding at Jan. 31, 2014	115,722	115,722