SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND PRACTICES - New Accounting Standards - Effects of Adoption of ASU 2014-09 on Consolidated Financial Statements (Details) - USD ($) $ 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	Jan. 01, 2018
ASSETS
Prepaid expenses and other current assets	$ 19,445								$ 17,950					$ 19,445	$ 17,950
LIABILITIES AND EQUITY
Deferred income taxes	6,106								18,394					6,106	18,394
Retained earnings	81,450								135,486					81,450	135,486
Statement of Operations
Revenues	309,799		$ 290,856		$ 343,889		$ 302,385		316,334		$ 285,067	$ 312,256	$ 286,554	1,246,929	1,200,211	$ 1,196,696
Operating expenses														918,673	890,212	868,144
Benefit for income taxes														(31,063)	(53,078)	(3,093)
Net loss	3,985	[1]	$ (23,526)	[1]	$ (31,341)	[1]	$ (12,264)	[1]	$ 19,667	[1]	$ (83,528)	$ (11,086)	$ (9,508)	(63,146)	$ (84,455)	$ (12,676)
Adjustments to apply ASC 606 | ASU 2014-09
ASSETS
Prepaid expenses and other current assets	3,124													3,124			$ 8,500
LIABILITIES AND EQUITY
Deferred income taxes	612													612
Retained earnings	$ 2,512													2,512
Statement of Operations
Revenues														(4,765)
Operating expenses														905
Benefit for income taxes														(1,403)
Net loss														$ (4,267)

[1] Income (loss) from continuing operations, net income (loss) and the related earnings (loss) per share amounts for each of the quarters in 2018 and the fourth quarter of 2017 are revised from those originally reported to correct errors in income tax expense (benefit) associated with the measurement of valuation allowances on deferred tax assets. Based on an analysis of quantitative and qualitative factors, the Company determined the related impacts were not material to its previously filed annual or interim consolidated financial statements, and therefore, amendments of previously filed reports are not required.