GOODWILL, TRADE NAMES, AND OTHER INTANGIBLE ASSETS - Acquired Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 88,308	$ 89,487
Accumulated Amortization	39,583	34,305
Intangible assets subject to amortization, net carrying amount	48,725	55,182
Trade names, indefinite-lived	5,900	20,402
Databases [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	30,530	30,530
Accumulated Amortization	11,506	9,216
Intangible assets subject to amortization, net carrying amount	19,024	21,314
Customer relationships [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	49,758	49,758
Accumulated Amortization	25,771	23,296
Intangible assets subject to amortization, net carrying amount	23,987	26,462
Non-compete agreements [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	320	320
Accumulated Amortization	145	97
Intangible assets subject to amortization, net carrying amount	175	223
Trade names [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,700	8,879
Accumulated Amortization	2,161	1,696
Intangible assets subject to amortization, net carrying amount	$ 5,539	$ 7,183