SUMMARY OF QUARTERLY FINANCIAL INFORMATION Quarterly Financial Information Disclosure (Details) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended								12 Months Ended
	Nov. 29, 2011	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Financial Information Disclosure [Abstract]
Revenue		$ 38,213	$ 36,656	$ 37,845	$ 37,447	$ 36,044	$ 36,302	$ 33,997	$ 34,702	$ 150,161	$ 141,045	$ 134,445
Income from continuing operations attributable to Common Shareholders		3,789	3,843	4,245	8,185	6,589	4,592	12,250	4,829	20,062	28,260	26,574
Income from discontinued operations attributable to Common Shareholders		4,098	168	25,989	1,238	423	525	548	301	31,493	1,797	4,559
Net income attributable to Common Shareholders		$ 7,887	$ 4,011	$ 30,234	$ 9,423	$ 7,012	$ 5,117	$ 12,798	$ 5,130	$ 51,555	$ 30,057	$ 31,133
Net income attributable to Common Shareholders per Common Share - basic:
Income from continuing operations		$ 0.09	$ 0.10	$ 0.11	$ 0.20	$ 0.16	$ 0.12	$ 0.30	$ 0.12	$ 0.50	$ 0.70	$ 0.70
Income from discontinued operations		$ 0.10	$ 0.00	$ 0.64	$ 0.03	$ 0.01	$ 0.01	$ 0.02	$ 0.01	$ 0.77	$ 0.05	$ 0.12
Net income per share		$ 0.19	$ 0.10	$ 0.75	$ 0.23	$ 0.17	$ 0.13	$ 0.32	$ 0.13	$ 1.27	$ 0.75	$ 0.82
Net income attributable to Common Shareholders per Common Share - diluted:
Income from continuing operations		$ 0.09	$ 0.10	$ 0.10	$ 0.20	$ 0.16	$ 0.12	$ 0.30	$ 0.12	$ 0.49	$ 0.70	$ 0.70
Income from discontinued operations		$ 0.10	$ 0.00	$ 0.64	$ 0.03	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.77	$ 0.04	$ 0.12
Net income per share		$ 0.19	$ 0.10	$ 0.74	$ 0.23	$ 0.17	$ 0.13	$ 0.31	$ 0.13	$ 1.26	$ 0.74	$ 0.82
Cash dividends declared per Common Share	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.72	$ 0.72	$ 0.75
Weighted average Common Shares outstanding:
Basic		41,785,261	40,339,958	40,333,575	40,317,603	40,257,378	40,169,141	40,134,706	39,980,646
Diluted		42,066,390	40,628,781	40,633,317	40,580,173	40,594,009	40,430,998	40,371,812	40,149,931	40,986,000	40,406,000	38,242,000