STOCKHOLDERS' EQUITY - Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands														12 Months Ended
	Feb. 20, 2019	Dec. 04, 2018	Aug. 22, 2018	Jun. 04, 2018	Mar. 06, 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. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Dividend declared
Payment of special cash dividends														$ 1,575	$ 4,872	$ 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)			$ 0.12500	$ 0.12500			$ 0.125	$ 0.125		$ 0.125			$ 0.21875
Common Stock, Excluding Private Repurchase Participants
Dividend declared
Dividends declared, common (in usd per share)		$ 0.12500			$ 0.12500	$ 0.73				$ 1.98		$ 0.28
Payment of special cash dividends						$ 1,575			$ 4,271		$ 601