Sale-Leaseback Arrangement (Details) (USD $) In Thousands, unless otherwise specified			9 Months Ended
Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Canonsburg Office, New Company Headquarters [Member]
Sale Leaseback Transaction [Line Items]
Original Lease Term			15 years 3 months
Construction in progress leased facility	$ 11,222	$ 0

Carrying amount of the accumulated asset as of the balance sheet date where the Company is deemed to be the owner during the asset's construction period.

No definition available.

Name:	anss_ConstructionInProgressLeasedFacility
Namespace Prefix:	anss_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant