QUARTERLY FINANCIAL INFORMATION (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information [Abstract]
Change in fair value of contingent consideration	$ 6,800								$ 10,788	$ 23,931	$ 0
Revenue	202,672	$ 197,057	$ 184,101	$ 181,035	$ 160,954	$ 171,494	$ 152,773	$ 132,515	764,865	617,736	384,402
Operating income (loss)	2,428	20,290	18,123	15,350	(175)	17,455	8,969	6,884	56,191	33,133	52,112
Income (loss) from continuing operations	251	28,362	44,849	35,857	(6,518)	10,131	8,007	7,798	109,319	19,418	31,208
Loss from discontinued operations	(3,551)	(2,634)	(2,302)	(4,333)	(1,208)	(1,011)	(689)	(932)	(12,820)	(3,840)	(3,714)
Net income (loss) and comprehensive income (loss)	$ (3,300)	$ 25,728	$ 42,547	$ 31,524	$ (7,726)	$ 9,120	$ 7,318	$ 6,866	$ 96,499	$ 15,578	$ 27,494
Basic (in dollars per share)	$ 0.02	$ 2.22	$ 3.61	$ 2.97	$ (0.54)	$ 0.84	$ 0.67	$ 0.66	$ 8.74	$ 1.63	$ 2.64
Diluted (in dollars per share)	0.02	2.05	3.17	2.41	(0.54)	0.74	0.59	0.58	7.75	1.42	2.44
Income (loss) per share from discontinued operations:
Basic (in dollars per share)	(0.28)	(0.21)	(0.19)	(0.36)	(0.10)	(0.08)	(0.06)	(0.08)
Diluted (in dollars per share)	(0.26)	(0.19)	(0.16)	(0.29)	(0.10)	(0.07)	(0.05)	(0.07)
Income per share from continuing operations:
Basic (in dollars per share)	(0.26)	2.01	3.43	2.61	(0.64)	0.76	0.61	0.58	7.72	1.30	2.33
Diluted (in dollars per share)	$ (0.24)	$ 1.86	$ 3.01	$ 2.12	$ (0.64)	$ 0.66	$ 0.54	$ 0.51	$ 6.85	$ 1.14	$ 2.15
Charitable Contribution, Total					$ 10,000				$ 10,000
Provisional estimate for remeasurement of deferred tax assets and liabilities from Tax Cuts and Jobs Act					$ 9,100				$ 270	$ 9,062	$ 0