EARNINGS PER SHARE - Summary of Components Used to Calculate Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Income from continuing operations	$ 9,787	$ 22,445	$ 34,083	$ 33,206	$ 10,374	$ 27,198	$ 21,955	$ 48,734	$ 99,521	$ 108,261	$ 125,256
Less: Preferred dividends									(17,408)	(18,232)	(16,588)
Premium on redemption of preferred stock									(2,572)	(2,125)	0
Allocation to participating securities									(307)	(342)	(118)
Attributable to non-controlling interest									307	456	819
Net income attributable to common stockholders, net of amount allocated to participating securities									$ 78,927	$ 87,106	$ 107,731
Denominator:
Weighted average common shares outstanding - basic (in shares)									99,406	86,874	85,920
Dilutive effect of equity-based compensation awards (in shares)									374	469	1,224
Weighted average common shares outstanding - diluted (in shares)									99,780	87,343	87,144
Basic (in dollars per share)	$ 0.02	$ 0.18	$ 0.30	$ 0.31					$ 0.79	$ 1.00	$ 1.25
Diluted (in dollars per share)	$ 0.02	$ 0.17	$ 0.30	$ 0.31					$ 0.79	$ 1.00	$ 1.24