Summary Selected Quarterly Financial Data (unaudited) (Tables)

12 Months Ended

Dec. 31, 2012

Summary Selected Quarterly Financial Data (unaudited) [Abstract]

Summary of selected unaudited consolidated quarterly financial data

	Three Months Ended
	March 31, 2012		June 30, 2012		September 30, 2012		December 31, 2012
Total revenues	$	70,260	$	79,093	$	68,511	$	75,066
Income from operations	$	4,628	$	11,461	$	7,177	$	7,393
Net income	$	3,181	$	7,769	$	10,373	$	4,251
Basic income per common share	$	0.14	$	0.34	$	0.46	$	0.19
Diluted income per common share	$	0.14	$	0.34	$	0.45	$	0.19

	Three Months Ended
	March 31, 2011		June 30, 2011		September 30, 2011		December 31, 2011
Total revenues	$	65,742	$	73,450	$	69,774	$	74,650
Income from operations	$	4,198	$	9,616	$	9,749	$	13,434
Net income	$	2,911	$	5,470	$	5,732	$	8,897
Basic income per common share	$	0.13	$	0.24	$	0.25	$	0.39
Diluted income per common share	$	0.13	$	0.24	$	0.25	$	0.38