ACQUISITIONS - CastleLine (Details) - USD ($) shares in Thousands, $ in Thousands		9 Months Ended
	Jul. 17, 2015	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2016	Dec. 31, 2015
Acquisitions
Acquisition of businesses with restricted shares		$ 0	$ 14,427
Goodwill		$ 89,905			$ 82,801
CastleLine
Acquisitions
Cash paid at acquisition	$ 12,300
Accounts payable	$ 10,500
Contingent consideration arrangements, payment period	4 years
Number of shares exchanged for acquisition (in thousands)	495
Acquisition of businesses with restricted shares	$ 14,400
Contingent consideration arrangements, range of outcomes, value, high	3,800
Cash				$ 1,088
Accounts receivable, net				100
Prepaid expenses				20
Restricted cash				2,501
Non-compete agreements				1,130
Databases/other				1,800
Customer relationships				395
Trademarks and trade names				160
Deferred taxes				356
Goodwill				26,730
Total assets				34,280
Accounts payable and accrued expenses				(837)
Deferred revenue				0
Purchase price				33,443
CastleLine | Initial purchase price allocation
Acquisitions
Business combination, consideration transferred	33,400
Cash	1,088
Accounts receivable, net	510
Prepaid expenses	66
Restricted cash	2,501
Non-compete agreements	1,105
Databases/other	465
Customer relationships	395
Trademarks and trade names	150
Deferred taxes	0
Goodwill	28,125
Total assets	34,405
Accounts payable and accrued expenses	(875)
Deferred revenue	(87)
Purchase price	$ 33,443
CastleLine | Adjustments
Acquisitions
Cash				0
Accounts receivable, net				(410)
Prepaid expenses				(46)
Restricted cash				0
Non-compete agreements				25
Databases/other				1,335
Customer relationships				0
Trademarks and trade names				10
Deferred taxes				356
Goodwill				(1,395)
Total assets				(125)
Accounts payable and accrued expenses				38
Deferred revenue				87
Purchase price				$ 0