Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 16,775	$ 14,372
Other comprehensive income:
Change in fair value of derivatives net of reclassification to interest expense	(1,929)	1,539
Total comprehensive income	14,846	15,911
Comprehensive income attributable to noncontrolling interest	(90)	(102)
Comprehensive income attributable to common shareholders	$ 14,756	$ 15,809