BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Jan. 01, 2017
Defined Contribution 401(k) Plan
Expense recorded for discretionary amounts contributed	$ 1,200	$ 1,200	$ 1,200
New Accounting Pronouncements
Deferred revenue	10,108	9,802
Other current liabilities	7,030	9,414
Retained earnings decrease	(590,655)	(626,600)
Cumulative effect (decrease) increase of an accounting change				$ (10,448)	$ 0
Restricted cash	5,752	3,837	$ 4,127
Accumulated other comprehensive income (loss)
New Accounting Pronouncements
Cumulative effect (decrease) increase of an accounting change				(733)
Retained earnings
New Accounting Pronouncements
Cumulative effect (decrease) increase of an accounting change				(9,715)	(932)
Accounting Standards Update 2016-09 | Retained earnings
New Accounting Pronouncements
Cumulative effect (decrease) increase of an accounting change					$ (900)
Accounting Standards Update 2016-09 | Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements
Deferred revenue				11,200
Accounting Standards Update 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements
Deferred revenue	(1,511)
Unbilled accounts receivable				1,100
Other current liabilities	(3,490)			300
Retained earnings decrease	(4,277)			10,400
Accounting Standards Update 2016-01 | Accumulated other comprehensive income (loss)
New Accounting Pronouncements
Cumulative effect (decrease) increase of an accounting change				(700)
Accounting Standards Update 2016-01 | Retained earnings
New Accounting Pronouncements
Cumulative effect (decrease) increase of an accounting change				$ 700
Accounting Standards Update 2016-02
New Accounting Pronouncements
Operating lease, right-of-use, estimated asset and liability (approximately)	$ 42,400
Furniture and fixtures
Premises and Equipment, Net
Estimated useful lives	5 years
Office equipment
Premises and Equipment, Net
Estimated useful lives	5 years
Computer hardware
Premises and Equipment, Net
Estimated useful lives	5 years
Computer software | Minimum
Premises and Equipment, Net
Estimated useful lives	3 years
Computer software | Maximum
Premises and Equipment, Net
Estimated useful lives	7 years
Leasehold improvements | Maximum
Premises and Equipment, Net
Estimated useful lives	10 years
Lenders One
Principles of Consolidation
Total assets	$ 2,700	4,600
Total liabilities	$ 1,300	$ 3,100