SUMMARIZED CONDENSED CONSOLIDATING INFORMATION (Condensed Consolidating Statement of Income) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Rental income	$ 31,699,000	$ 25,420,000	$ 94,692,000	$ 73,903,000
Interest and other income	1,227,000	618,000	2,531,000	979,000
Total revenues	32,926,000	26,038,000	97,223,000	74,882,000
Expenses:
Depreciation and amortization	8,258,000	7,496,000	24,726,000	22,356,000
Interest	9,739,000	9,085,000	29,884,000	24,681,000
General and administrative	3,057,000	3,778,000	11,196,000	11,588,000
Total expenses	21,054,000	20,359,000	65,806,000	58,625,000
Loss on extinguishment of debt	(351,000)	(453,000)	(10,101,000)	(703,000)
Other income	300,000		(600,000)
Total other income (expense)	(51,000)	(453,000)	(10,701,000)	(703,000)
(Income) loss in subsidiary	0	0	0	0
Net income	11,821,000	5,226,000	20,716,000	15,554,000
Preferred Stock Dividends, Income Statement Impact	2,579,000	0	5,406,000	0
Net income attributable to common stockholders	9,242,000	5,226,000	15,310,000	15,554,000
Net income per common share, basic (USD per shares)	$ 0.25	$ 0.14	$ 0.41	$ 0.42
Net income per common share, diluted (USD per shares)	$ 0.24	$ 0.14	$ 0.41	$ 0.42
Weighted-average number of common shares outstanding, basic (in shares)	37,358,334	37,178,162	37,334,120	37,121,384
Weighted-average number of common shares outstanding, diluted (in shares)	37,828,573	37,465,114	37,777,458	37,276,013
Parent Company [Member]
Revenues:
Rental income	0	0	0	0
Interest and other income	13,000	7,000	82,000	15,000
Total revenues	13,000	7,000	82,000	15,000
Expenses:
Depreciation and amortization	13,000	12,000	38,000	36,000
Interest	0	0	0	0
General and administrative	2,996,000	3,627,000	10,671,000	10,548,000
Total expenses	3,009,000	3,639,000	10,709,000	10,584,000
Loss on extinguishment of debt	0	0	0	0
Other income	0		0
Total other income (expense)	0	0	0	0
(Income) loss in subsidiary	14,817,000	8,858,000	31,343,000	26,123,000
Net income	11,821,000	5,226,000	20,716,000
Preferred Stock Dividends, Income Statement Impact	2,579,000		5,406,000
Net income attributable to common stockholders	9,242,000		15,310,000	15,554,000
Issuers [Member]
Revenues:
Rental income	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	0	0	0	0
Expenses:
Depreciation and amortization	0	0	0	0
Interest	7,147,000	6,162,000	21,585,000	15,675,000
General and administrative	0	0	4,000	2,000
Total expenses	7,147,000	6,162,000	21,589,000	15,677,000
Loss on extinguishment of debt	0	0	(9,750,000)	0
Other income	0		0
Total other income (expense)	0	0	(9,750,000)	0
(Income) loss in subsidiary	21,964,000	15,020,000	62,682,000	41,800,000
Net income	14,817,000	8,858,000	31,343,000
Preferred Stock Dividends, Income Statement Impact	0		0
Net income attributable to common stockholders	14,817,000		31,343,000	26,123,000
Combined Guarantor Subsidiaries [Member]
Revenues:
Rental income	24,380,000	18,972,000	72,733,000	54,558,000
Interest and other income	1,214,000	611,000	2,449,000	964,000
Total revenues	25,594,000	19,583,000	75,182,000	55,522,000
Expenses:
Depreciation and amortization	6,365,000	5,446,000	18,983,000	16,170,000
Interest	817,000	708,000	2,797,000	1,887,000
General and administrative	41,000	133,000	453,000	971,000
Total expenses	7,223,000	6,287,000	22,233,000	19,028,000
Loss on extinguishment of debt	(351,000)	0	(351,000)	0
Other income	300,000		(600,000)
Total other income (expense)	(51,000)	0	(951,000)	0
(Income) loss in subsidiary	982,000	(52,000)	2,892,000	94,000
Net income	19,302,000	13,244,000	54,890,000
Preferred Stock Dividends, Income Statement Impact	0		0
Net income attributable to common stockholders	19,302,000		54,890,000	36,588,000
Combined Non-Guarantor Subsidiaries [Member]
Revenues:
Rental income	7,319,000	6,448,000	21,959,000	19,345,000
Interest and other income	0	0	0	0
Total revenues	7,319,000	6,448,000	21,959,000	19,345,000
Expenses:
Depreciation and amortization	1,880,000	2,038,000	5,705,000	6,150,000
Interest	1,775,000	2,215,000	5,502,000	7,119,000
General and administrative	20,000	18,000	68,000	67,000
Total expenses	3,675,000	4,271,000	11,275,000	13,336,000
Loss on extinguishment of debt	0	(453,000)	0	(703,000)
Other income	0		0
Total other income (expense)	0	(453,000)	0	(703,000)
(Income) loss in subsidiary	0	0	0	0
Net income	3,644,000	1,724,000	10,684,000
Preferred Stock Dividends, Income Statement Impact	0		0
Net income attributable to common stockholders	3,644,000		10,684,000	5,306,000
Elimination [Member]
Revenues:
Rental income	0	0	0	0
Interest and other income	0	0	0	0
Total revenues	0	0	0	0
Expenses:
Depreciation and amortization	0	0	0	0
Interest	0	0	0	0
General and administrative	0	0	0	0
Total expenses	0	0	0	0
Loss on extinguishment of debt	0	0	0	0
Other income	0		0
Total other income (expense)	0	0	0	0
(Income) loss in subsidiary	(37,763,000)	(23,826,000)	(96,917,000)	(68,017,000)
Net income	(37,763,000)	(23,826,000)	(96,917,000)
Preferred Stock Dividends, Income Statement Impact	0		0
Net income attributable to common stockholders	$ (37,763,000)		$ (96,917,000)	$ (68,017,000)