Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 9,856	$ 18,058
Other comprehensive income (loss):
Unrealized gain (loss) on valuation of interest rate swap agreements	(7,390)	4,180
Less: amount reclassified into interest expense	149	599
Other comprehensive income (loss)	(7,241)	4,779
Comprehensive income	2,615	22,837
Net income attributable to non-controlling interests and private perpetual preferred unitholders	(4,179)	(8,290)
Other comprehensive (income) loss attributable to non-controlling interests	2,969	(2,160)
Comprehensive income attributable to common stockholders	$ 1,405	$ 12,387