Discontinued Operations and Impairments (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014 item	Mar. 31, 2013 item	Dec. 31, 2014 item
Discontinued operations
Provisions for impairment	$ 1,700,000	$ 456,000
Number of impaired properties sold	1	5
Number of impaired properties held-for-sale	3
Number of properties held-for-sale	11
Number of properties previously held for sale and included in income from discontinued operations			1
Number of properties not previously classified as held for sale and included in income from continuing operations			10
Amount of debt assumed by buyers of investment properties, or repaid as a result of investment property sales	0
Income from discontinued operations
Gain on sales of investment properties	2,607,000	38,559,000
Rental revenue	63,000	2,787,000
Tenant reimbursements	2,000	33,000
Other revenue	8,000	11,000
Depreciation and amortization		(495,000)
Property expenses (including reimbursable)	(101,000)	(540,000)
Provisions for impairment		(456,000)
Crest's income (loss) from discontinued operations	498,000	(40,000)
Income from discontinued operations	$ 3,077,000	$ 39,859,000
Per common share, basic and diluted (in dollars per share)	$ 0.01	$ 0.23
Automotive parts industry
Discontinued operations
Number of impaired properties		1
Child care industry
Discontinued operations
Number of impaired properties		2
Pet supplies and services industry
Discontinued operations
Number of impaired properties		1
Restaurant - casual dining industry
Discontinued operations
Number of impaired properties held-for-sale	2
Number of impaired properties		1
Consumer electronics industry
Discontinued operations
Number of impaired properties held-for-sale	1
Home furnishings industry
Discontinued operations
Number of impaired properties held-for-sale	1