CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Livermore Software Technology Corporation	Analytical Graphics, Inc.	Common Stock	Common Stock Livermore Software Technology Corporation	Common Stock Analytical Graphics, Inc.	Additional Paid-In Capital	Additional Paid-In Capital Livermore Software Technology Corporation	Additional Paid-In Capital Analytical Graphics, Inc.	Retained Earnings	Treasury Stock	Treasury Stock Livermore Software Technology Corporation	Treasury Stock Analytical Graphics, Inc.	Accumulated Other Comprehensive (Loss)/Income
Beginning balance at Dec. 31, 2018	$ 2,649,547			$ 932			$ 867,462			$ 2,919,411	$ (1,075,879)			$ (62,379)
Beginning balance, shares at Dec. 31, 2018				93,236							9,602
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisition activity		$ 307,173			$ 14			$ 307,159
Acquisition activity, shares					1,392
Treasury shares acquired	$ (59,116)										$ (59,116)
Treasury shares acquired, shares	330										330
Stock-based compensation activity	$ 107,482						14,318				$ 93,164
Stock-based compensation activity, shares											(1,039)
Other comprehensive (loss)/income	(3,002)													(3,002)
Net income for the year	451,295									451,295
Ending balance at Dec. 31, 2019	3,453,379			$ 946			1,188,939			3,370,706	$ (1,041,831)			(65,381)
Ending balance, shares at Dec. 31, 2019				94,628							8,893
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisition activity		$ 1,531	$ 218,348			$ 7		$ 1,030	$ 218,108			$ 501	$ 233
Acquisition activity, shares						638
Acquisition activity, treasury shares												(6)	(3)
Treasury shares acquired	$ (161,029)										$ (161,029)
Treasury shares acquired, shares	690										690
Stock-based compensation activity	$ 104,150						26,126				$ 78,024
Stock-based compensation activity, shares											(880)
Other comprehensive (loss)/income	47,606													47,606
Net income for the year	433,887									433,887
Ending balance at Dec. 31, 2020	4,097,872			$ 953			1,434,203			3,804,593	$ (1,124,102)			(17,775)
Ending balance, shares at Dec. 31, 2020				95,266							8,694
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisition activity			$ 3,888						$ 3,069				$ 819
Acquisition activity, shares						1
Acquisition activity, treasury shares													(10)
Treasury shares acquired	$ (134,679)										$ (134,679)
Treasury shares acquired, shares	347										347
Stock-based compensation activity	$ 100,677						28,422				$ 72,255
Stock-based compensation activity, shares											(843)
Other comprehensive (loss)/income	(38,337)													(38,337)
Net income for the year	454,627									454,627
Ending balance at Dec. 31, 2021	$ 4,484,048			$ 953			$ 1,465,694			$ 4,259,220	$ (1,185,707)			$ (56,112)
Ending balance, shares at Dec. 31, 2021				95,267							8,188