Acquisitions (Tables)

12 Months Ended

Dec. 31, 2012

Business Acquisition [Line Items]

Business Acquisition, Pro forma Information

	Year Ended December 31,
	2011		2010
(in thousands, except per share data)	(Unaudited)		(Unaudited)
Total revenue	$	730,632	$	624,283
Net income	$	181,718	$	144,605
Earnings per share:
Basic	$	1.97	$	1.59
Diluted	$	1.93	$	1.55

Esterel Technologies, S.A.

Business Acquisition [Line Items]

Fair Value of Consideration Transferred

Fair Value of Consideration Transferred:

(in thousands)
Cash	$	58,150

Recognized Amounts of Identifiable Assets Acquired and Liabilities Assumed

Recognized Amounts of Identifiable Assets Acquired and Liabilities Assumed:

(in thousands)
Cash	$	13,075
Accounts receivable and other tangible assets	4,737
Customer relationships (12-year life)	21,421
Developed software (10-year life)	10,717
Platform trade name (indefinite life)	2,695
Accounts payable and other liabilities	(4,936		)
Deferred revenue	(1,139		)
Net deferred tax liabilities	(9,286		)
Total identifiable net assets	$	37,284
Goodwill	$	20,866

Apache Design Solutions, Inc.

Business Acquisition [Line Items]

Fair Value of Consideration Transferred

Fair Value of Consideration Transferred:

(in thousands)
Cash	$	301,306
Contingent consideration	9,501
ANSYS replacement stock options	3,170
Total consideration transferred at fair value	$	313,977

Recognized Amounts of Identifiable Assets Acquired and Liabilities Assumed

Recognized Amounts of Identifiable Assets Acquired and Liabilities Assumed:

(in thousands)
Cash and short-term investments	$	31,948
Accounts receivable and other tangible assets	6,011
Developed software (7-year life)	82,500
Customer relationships (15-year life)	36,100
Contract backlog (3-year life)	13,500
Platform trade names (indefinite lives)	21,900
Apache trade name (6-year life)	2,100
Accounts payable and other liabilities	(16,867		)
Deferred revenue	(10,100		)
Net deferred tax liabilities	(47,229		)
Total identifiable net assets	$	119,863
Goodwill	$	194,114