SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information Narrative (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Internally developed computer software								$ 75,800
Asset impairment charge		$ 4,400	$ 2,100	$ 75,200	$ 1,323	$ 4,432	$ 77,268
Depreciation					14,400	17,200	20,000
Amortization of deferred debt issuance costs					700	700	800
Unamortized debt issuance costs	$ 1,900	2,700			$ 1,900	2,700
Unamortized debt issuance costs, weighted average amortization period, years					2 years 8 months 12 days
Deferred tax assets	56,064	$ 107,940			$ 56,064	107,940
Decrease in deferred income tax expense from remeasurement of deferred taxes due to change in tax rate (Tax Cuts and Jobs Act)	$ 21,400
Non-cash compensation					16,295	16,401	11,824
Share-based compensation, tax benefit recognized					6,400	6,400	4,700
Advertising expense					$ 6,500	$ 7,800	$ 6,900
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible assets					3 years
Acquired Names [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible assets					5 years