Other Assets (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Dec. 31, 2014
Other assets, net
Property and equipment, net	$ 1,400,000		$ 1,400,000			$ 2,127,000
Land held for development	188,000		188,000			188,000
Intangibles, net						6,677,000
Deferred expense on straightlined third-party tenant leases	3,206,000		3,206,000			1,426,000
Other receivables	1,337,000		1,337,000			2,094,000
Other	1,946,000		1,946,000			1,973,000
Total other assets, net	8,077,000		8,077,000			14,485,000
Amortization expense			6,048,000	$ 5,507,000
BuyEfficient, LLC
Other assets, net
Accumulated amortization	0		0			2,400,000
Amortization expense	100,000	$ 100,000	$ 400,000	$ 400,000
BuyEfficient, LLC | Minimum
Other assets, net
Useful life of intangibles			7 years
BuyEfficient, LLC | Maximum
Other assets, net
Useful life of intangibles			20 years
Rochester Portfolio | Preferred equity investment
Other assets, net
Carrying value of asset net of deferred gain					$ 0	$ 0
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | BuyEfficient, LLC
Other assets, net
Intangible assets written off due to sale of asset	$ 6,200,000		$ 6,200,000