STOCKHOLDERS' EQUITY - Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands															12 Months Ended
	Mar. 06, 2018	Jan. 11, 2018	Dec. 18, 2017	Dec. 06, 2017	Sep. 07, 2017	Jun. 27, 2017	Jun. 12, 2017	Apr. 24, 2017	Apr. 05, 2017	Mar. 08, 2017	Dec. 06, 2016	Sep. 12, 2016	Jun. 10, 2016	Mar. 08, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividend declared
Payment of special cash dividends															$ 4,872	$ 0	$ 0
Subsequent event
Dividend declared
Dividends declared, common (in usd per share)	$ 0.125
Common Stock
Dividend declared
Dividends declared, common (in usd per share)				$ 0.125	$ 0.125		$ 0.125			$ 0.21875	$ 0.21875	$ 0.21875	$ 0.21875	$ 0.21875
Common Stock, Excluding Private Repurchase Participants [Member]
Dividend declared
Dividends declared, common (in usd per share)			$ 0.73				$ 1.98		$ 0.28
Payment of special cash dividends						$ 4,271		$ 601
Common Stock, Excluding Private Repurchase Participants [Member] | Subsequent event
Dividend declared
Payment of special cash dividends		$ 1,575