Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 26,784	$ 29,230	$ 55,570	$ 77,472
Other comprehensive income (loss):
Unrealized gain (loss) on valuation of interest rate swap agreements	(6,256)	3,884	(25,992)	9,827
Less: amount reclassified into interest expense	319	427	637	1,562
Other comprehensive income (loss)	(5,937)	4,311	(25,355)	11,389
Comprehensive income (loss)	20,847	33,541	30,215	88,861
Net income attributable to non-controlling interests and private perpetual preferred unitholders	(10,902)	(12,888)	(22,924)	(34,711)
Other comprehensive (income) loss attributable to non-controlling interests	2,347	(1,881)	10,269	(5,045)
Comprehensive income attributable to common stockholders	$ 12,292	$ 18,772	$ 17,560	$ 49,105