Quarterly Financial Information (Summary of Selected Quarterly Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 105,443	$ 103,465	$ 98,687	$ 94,768	$ 92,690	$ 88,890	$ 68,117	$ 61,386	$ 402,363	$ 311,083	$ 217,789
Operating income	11,092	8,505	8,225	10,235	7,243	11,095	7,266	10,379	38,057	35,983	35,274
Net income	5,481	6,538	5,807	6,859	5,334	8,238	5,520	5,037	24,685	24,129	19,103
Net income available to common stockholders - basic	$ 4,806	$ 5,730	$ 5,100	$ 5,889	$ 4,603	$ 7,009	$ 4,632	$ 4,082	$ 21,525	$ 20,326	$ 15,072
Basic (in dollars per share)	$ 0.10	$ 0.12	$ 0.11	$ 0.14	$ 0.11	$ 0.17	$ 0.13	$ 0.13	$ 0.47	$ 0.54	$ 0.52
Diluted (in dollars per share)	$ 0.10	$ 0.12	$ 0.10	$ 0.14	$ 0.11	$ 0.17	$ 0.12	$ 0.13	$ 0.46	$ 0.53	$ 0.51
Qualitytech, LP [Member]
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 105,443	$ 103,465	$ 98,687	$ 94,768	$ 92,690	$ 88,890	$ 68,117	$ 61,386	$ 402,363	$ 311,083	$ 217,789
Operating income	11,092	8,505	8,225	10,235	7,243	11,095	7,266	10,379	38,057	35,983	35,274
Net income	$ 5,481	$ 6,538	$ 5,807	$ 6,859	$ 5,334	$ 8,238	$ 5,520	$ 5,037	$ 24,685	$ 24,129	$ 19,103