Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income attributable to common stockholders	$ 25,122	$ 32,643	$ 37,849	$ 45,777
Other comprehensive income:
Unrealized loss on derivatives, net of income taxes	(3,709)	165	(4,473)	(5,633)
Less interest expense on derivatives recognized into earnings, net of income taxes	(340)	(120)	(904)	(645)
Comprehensive income	$ 21,753	$ 32,928	$ 34,280	$ 40,789