LONG-TERM DEBT - Schedule of Long-Term Debt - Outstanding Indebtedness (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Mar. 11, 2015
Long-term debt
Face Value of Debt	$ 173,300
Credit Facility
Long-term debt
Face Value of Debt	$ 36,000
Credit Facility | LIBOR | Minimum
Long-term debt
Margin added to variable rate basis (as a percent)	1.35%
Credit Facility | LIBOR | Maximum
Long-term debt
Margin added to variable rate basis (as a percent)	2.25%
UBS Mortgage Note Payable
Long-term debt
Face Value of Debt	$ 7,300
Stated interest rate (as a percent)	3.655%
Wells Fargo Mortgage Note Payable Originated September 30, 2014
Long-term debt
Face Value of Debt	$ 30,000
Stated interest rate (as a percent)	4.33%
Wells Fargo Mortgage Note Payable Originated April 15, 2016
Long-term debt
Face Value of Debt	$ 25,000
Wells Fargo Mortgage Note Payable Originated April 15, 2016 | LIBOR
Long-term debt
Margin added to variable rate basis (as a percent)	1.90%
4.50% Convertible Senior Notes due 2020
Long-term debt
Face Value of Debt	$ 75,000	$ 75,000
Stated interest rate (as a percent)	4.50%