NET INCOME (LOSS) PER COMMON SHARE - Components of Computation of Basic and Diluted Net Income per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator for basic net income (loss) per common share:
Net (loss) income					$ (35,338)	$ 50,072	$ 79,589
Preferred stock dividends					(19,368)	(19,368)	(17,442)
Earnings participation of unvested equity awards					(100)	(102)	(150)
Numerator for basic net income (loss) per common share					$ (54,806)	$ 30,602	$ 61,997
Denominator for basic net income (loss) per common share:
Average number of shares of common stock outstanding (in shares)					89,349	91,565	96,023
Average unvested stock awards outstanding (in shares)					(627)	(451)	(305)
Denominator for basic net income per common share (in shares)					88,722	91,114	95,718
Basic net income per common share (in dollars per share)	$ 0.30	$ (0.02)	$ (0.80)	$ (0.15)	$ (0.62)	$ 0.34	$ 0.65
Numerator for diluted net income (loss) per common share:
Numerator for basic net income (loss) per common share					$ (54,806)	$ 30,602	$ 61,997
Denominator for diluted net income (loss) per common share:
Denominator for basic net income (loss) per common share					88,722	91,114	95,718
Net effect of dilutive equity awards						116	125
Denominator for diluted net income per common share (in shares)					88,722	91,230	95,843
Diluted net income per common share (in dollars per share)	$ 0.29	$ (0.02)	$ (0.80)	$ (0.15)	$ (0.62)	$ 0.34	$ 0.65