Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 32,897	$ 26,085	$ 74,242	$ 60,558
Other comprehensive income (loss):
Change in unrealized gain (loss) on valuation of interest rate swap agreements	930	(4,384)	(29,305)	(4,384)
Other comprehensive income (loss)	930	(4,384)	(29,305)	(4,384)
Comprehensive income	33,827	21,701	44,937	56,174
Net income attributable to non-controlling interests and private perpetual preferred unitholders	(16,924)	(14,865)	(39,752)	(35,080)
Other comprehensive (income) loss attributable to non-controlling interests	(979)	2,481	15,561	2,481
Comprehensive income attributable to common stockholders	$ 15,924	$ 9,317	$ 20,746	$ 23,575