Quarterly Operating Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 193,425	$ 216,321	$ 197,683	$ 163,435	$ 155,934	$ 169,676	$ 147,454	$ 125,712	$ 770,864	$ 598,776	$ 489,217
Net income (loss)	22,994	38,248	26,583	7,170	16,090	30,439	22,893	4,121	94,995	73,543	43,192
Net income (loss) attributable to the Company	22,915	38,119	26,491	7,143	15,950	30,165	22,673	4,078	94,668	72,866	42,918
Net income (loss) attributable to common shareholders	$ 16,428	$ 31,631	$ 20,004	$ 655	$ 9,462	$ 23,737	$ 16,591	$ (2,003)	$ 68,718	$ 47,787	$ 19,965
Net income (loss) per share available to common shareholders-basic (in dollars per share)	$ 0.23	$ 0.44	$ 0.28	$ 0.01					$ 0.95	$ 0.72	$ 0.32
Net income (loss) per share available to common shareholders-diluted (in dollars per share)	$ 0.23	$ 0.43	$ 0.27	$ 0.01					$ 0.94	$ 0.71	$ 0.32
Net income (loss) per share available to common shareholders, basic and diluted (in dollars per share)					$ 0.13	$ 0.36	$ 0.26	$ (0.03)