Estimated Amortization of Identified Intangible Assets for Next Five Years (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Disclosure Estimated Amortization Of Identified Intangible Assets For Next Five Years [Abstract]
Income from continuing operations	$ (0.10)	$ 0.16	$ 0.46	$ 0.33
Income from continuing operations	$ (0.10)	$ 0.16	$ 0.46	$ 0.33
Expected Amortization Expense [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Year One	$ 349		$ 349
Estimated amortization of identified intangible assets, year ending December 31, 2013	349		349
Estimated amortization of identified intangible assets, year ending December 31, 2014	251		251
Estimated amortization of identified intangible assets, year ending December 31, 2015	87		87
Estimated amortization of identified intangible assets, year ending December 31, 2016	$ 87		$ 87
Income from discontinued operations	$ 0.46	$ 0.03	$ 0.54	$ 0.04
Net income available for Common Shares	$ 0.36	$ 0.19	$ 1.00	$ 0.37
Income from discontinued operations	$ 0.46	$ 0.03	$ 0.53	$ 0.04
Net income available for Common Shares	$ 0.36	$ 0.19	$ 0.99	$ 0.37
Distributions declared per Common Share outstanding	$ 0.25	$ 0.219	$ 0.75	$ 0.656
Weighted average Common Shares outstanding – basic	83,021	82,380	83,023	82,274
Weighted average Common Shares outstanding – fully diluted	91,259	90,894	91,149	90,836