Segment and Related Information - Schedule of Segment Revenues and Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Software licenses and royalties	$ 17,107	$ 17,551	$ 35,330	$ 34,401
Subscriptions	40,947	33,968	81,049	68,057
Software services	47,372	46,040	92,390	88,470
Maintenance	89,412	78,743	176,271	154,775
Appraisal services	6,366	6,984	12,978	13,542
Hardware and other	7,919	5,686	10,647	9,020
Total revenues	209,123	188,972	408,665	368,265
Operating Income (Loss)	37,075	30,915	73,224	58,956
Operating segments
Segment Reporting Information [Line Items]
Operating Income (Loss)	45,898	40,048	90,915	76,910
Operating segments | Enterprise Software
Segment Reporting Information [Line Items]
Software licenses and royalties	15,354	16,439	31,928	32,093
Subscriptions	39,051	32,316	77,364	64,301
Software services	42,696	42,159	83,364	80,763
Maintenance	84,306	74,110	166,472	145,510
Hardware and other	3,295	2,942	6,023	5,977
Intercompany	2,486	1,612	4,649	2,772
Total revenues	187,188	169,578	369,800	331,416
Operating Income (Loss)	54,130	46,109	106,181	86,778
Operating segments | Appraisal and Tax
Segment Reporting Information [Line Items]
Software licenses and royalties	1,753	1,112	3,402	2,308
Subscriptions	1,896	1,652	3,685	3,756
Software services	4,676	3,881	9,026	7,707
Maintenance	5,106	4,633	9,799	9,265
Appraisal services	6,366	6,984	12,978	13,542
Hardware and other	0	0	0	16
Total revenues	19,797	18,262	38,890	36,594
Operating Income (Loss)	4,410	3,990	8,624	8,821
Corporate
Segment Reporting Information [Line Items]
Hardware and other	4,624	2,744	4,624	3,027
Intercompany	(2,486)	(1,612)	(4,649)	(2,772)
Total revenues	2,138	1,132	(25)	255
Operating Income (Loss)	$ (12,642)	$ (10,051)	$ (23,890)	$ (18,689)