Summary of Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

The following table summarizes selected Quarterly Financial Data for the Company on a historical basis for the years ended December 31, 2016 and 2015:

(in thousands except per share and per unit data)	First Quarter		Second Quarter	Third Quarter	Fourth Quarter
Year ended December 31, 2016
Operating Data:
Revenue	$	149,628	152,413	152,769	159,561
Net income attributable to common stockholders	$	47,877	34,810	5,305	55,868
Net income attributable to exchangeable operating partnership units	85		64	16	92
Net income attributable to common unit holders	$	47,962	34,874	5,321	55,960
Net income attributable to common stock and unit holders per share and unit:
Basic	$	0.49	0.36	0.05	0.53
Diluted	$	0.49	0.35	0.05	0.53
Year ended December 31, 2015
Operating Data:
Revenue	$	140,399	141,129	142,068	146,167
Net income attributable to common stockholders	$	25,174	32,480	53,731	17,609
Net income attributable to exchangeable operating partnership units	49		61	94	36
Net income attributable to common unit holders	$	25,223	32,541	53,825	17,645
Net income attributable to common stock and unit holders per share and unit:
Basic	$	0.27	0.35	0.57	0.18
Diluted	$	0.27	0.34	0.57	0.18