SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - PPE to Reimbursable Expenditures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Combinations
Bargain purchase gain		$ 146
Internal-Use Software and Website Development Costs
Capitalized costs associated with system conversion and website development	$ 300	600	$ 700
Goodwill
Percentage points of control premium added to the stock price as quoted on the Nasdaq Global Market	35.00%
Revenue growth rates per year under discounted cash flow model (as a percent)	3.00%
Rate employed to discount future excess cash flows (as a percent)	13.50%
Debt Issuance Costs
Amortization of debt issuance costs included in interest expense	$ 141	153	214
Revenue Recognition
Notice period to terminate agreements early due to breach or for convenience	30 days
Reimbursable Expenditures
Reimbursable expenditures	$ 10,100	$ 9,900	$ 10,400
Furniture Fixtures And Equipment | Minimum
Furniture, Fixtures and Equipment, net
Estimated useful life of assets	3 years
Furniture Fixtures And Equipment | Maximum
Furniture, Fixtures and Equipment, net
Estimated useful life of assets	5 years
Leasehold Improvements | Minimum
Furniture, Fixtures and Equipment, net
Estimated useful life of assets	3 years
Leasehold Improvements | Maximum
Furniture, Fixtures and Equipment, net
Estimated useful life of assets	5 years