GOODWILL, TRADE NAMES, AND OTHER INTANGIBLE ASSETS - Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 89,408	$ 89,487
Accumulated Amortization	38,598	34,305
Intangible assets subject to amortization, net carrying amount	50,810	55,182
Trade names, indefinite-lived	5,900	20,402
Total intangible assets, net	56,710	75,584
Databases [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	30,530	30,530
Accumulated Amortization	10,743	9,216
Intangible assets subject to amortization, net carrying amount	19,787	21,314
Customer relationships [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	49,758	49,758
Accumulated Amortization	24,946	23,296
Intangible assets subject to amortization, net carrying amount	24,812	26,462
Non-compete agreements [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	320	320
Accumulated Amortization	129	97
Intangible assets subject to amortization, net carrying amount	191	223
Trade names [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,800	8,879
Accumulated Amortization	2,780	1,696
Intangible assets subject to amortization, net carrying amount	$ 6,020	$ 7,183