Leases	12 Months Ended
Dec. 31, 2012
Leases [Abstract]
Leases	Leases The Company's executive offices and those related to certain domestic product development, marketing, production and administration are located in a 107,000 square foot office facility in Canonsburg, Pennsylvania. In May 2004, the Company entered into the first amendment to its existing lease agreement on this facility, effective January 1, 2004. The lease was extended from its original period to a period through 2014. The Company incurred lease rental expense related to this facility of $1.3 million in each of the years ended December 31, 2012, 2011 and 2010. The future minimum lease payments are $1.4 million per annum from January 1, 2013 through December 31, 2014. On September 14, 2012, the Company entered into a lease agreement for 186,000 square feet of rentable space to be located in a to-be-built office facility in Canonsburg, Pennsylvania, which will serve as the Company's new headquarters. The lease was effective as of September 14, 2012, but because the leased premises are to-be-built, the Company will not be obligated to pay rent until the later of (i) three months following the date that the leased premises are delivered to ANSYS, which delivery, subject to certain limited exceptions, shall occur no later than October 1, 2014, or (ii) January 1, 2015 (such later date, the “Commencement Date”). The term of the lease is 183 months, beginning on the Commencement Date. Absent the exercise of options in the lease for additional rentable space or early lease termination, the Company's base rent will be $4.3 million per annum for the first five years of the lease term, $4.5 million per annum for years six through ten and $4.7 million for years eleven through fifteen. As part of the acquisition of Apache on August 1, 2011, the Company acquired certain leased office property, including executive offices, which comprise a 52,000 square foot office facility in San Jose, California. In June 2012, the Company entered into a new lease for this property, with the lease term commencing July 1, 2012 and ending June 30, 2022. Total remaining minimum payments under the operating lease as of December 31, 2012 are $9.2 million, of which $0.9 million will be paid in 2013. The Company has entered into various other noncancellable operating leases for office space. Office space lease expense totaled $13.7 million, $12.8 million and $11.5 million for the years ended December 31, 2012, 2011 and 2010, respectively. Future minimum lease payments under noncancellable operating leases for office space in effect at December 31, 2012 are $12.6 million in 2013, $10.7 million in 2014, $10.0 million in 2015, $8.2 million in 2016 and $7.4 million in 2017.

Leases

12 Months Ended

Dec. 31, 2012

The Company's executive offices and those related to certain domestic product development, marketing, production and administration are located in a 107,000 square foot office facility in Canonsburg, Pennsylvania. In May 2004, the Company entered into the first amendment to its existing lease agreement on this facility, effective January 1, 2004. The lease was extended from its original period to a period through 2014. The Company incurred lease rental expense related to this facility of $1.3 million in each of the years ended December 31, 2012, 2011 and 2010. The future minimum lease payments are $1.4 million per annum from January 1, 2013 through December 31, 2014.

On September 14, 2012, the Company entered into a lease agreement for 186,000 square feet of rentable space to be located in a to-be-built office facility in Canonsburg, Pennsylvania, which will serve as the Company's new headquarters. The lease was effective as of September 14, 2012, but because the leased premises are to-be-built, the Company will not be obligated to pay rent until the later of (i) three months following the date that the leased premises are delivered to ANSYS, which delivery, subject to certain limited exceptions, shall occur no later than October 1, 2014, or (ii) January 1, 2015 (such later date, the “Commencement Date”). The term of the lease is 183 months, beginning on the Commencement Date. Absent the exercise of options in the lease for additional rentable space or early lease termination, the Company's base rent will be $4.3 million per annum for the first five years of the lease term, $4.5 million per annum for years six through ten and $4.7 million for years eleven through fifteen.

As part of the acquisition of Apache on August 1, 2011, the Company acquired certain leased office property, including executive offices, which comprise a 52,000 square foot office facility in San Jose, California. In June 2012, the Company entered into a new lease for this property, with the lease term commencing July 1, 2012 and ending June 30, 2022. Total remaining minimum payments under the operating lease as of December 31, 2012 are $9.2 million, of which $0.9 million will be paid in 2013.

The Company has entered into various other noncancellable operating leases for office space.

Office space lease expense totaled $13.7 million, $12.8 million and $11.5 million for the years ended December 31, 2012, 2011 and 2010, respectively. Future minimum lease payments under noncancellable operating leases for office space in effect at December 31, 2012 are $12.6 million in 2013, $10.7 million in 2014, $10.0 million in 2015, $8.2 million in 2016 and $7.4 million in 2017.