Earnings Per Share , Calculation of Numerator and Denominator (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator
Diluted earnings: net income available to common stockholders and unitholders	$ 22,671	$ 3,749	$ 35,445	$ 10,528
Denominator
Weighted average common shares outstanding	41,023	35,499	39,283	33,802
Weighted average unvested restricted stock outstanding	687	629	660	461
Basic Weighted average common shares outstanding	41,710	36,128	39,943	34,263
Add: dilutive securities	12	15	16	16
Diluted weighted average common shares	41,722	36,143	39,959	34,279
Basic	$ 0.54	$ 0.10	$ 0.89	$ 0.31
Diluted	$ 0.54	$ 0.10	$ 0.89	$ 0.31