Investments in Real Estate and Real Estate Under Construction - Schedule of Acquired Properties (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 Property	Dec. 31, 2013
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	$ 212,313	$ 532,538
Land and Land Estate	33,621	253,492
Building and Improvements	142,247	180,724
Above Market Lease Value		673
Lease in-place Value	36,445	97,649
Number of real estate properties	215
Construction in progress	14,946	4,306
Above Market Leases [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Weighted-average life of intangible assets (years)		15 years 3 months 18 days
Leases, Acquired-in-Place [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Weighted-average life of intangible assets (years)	37 years 6 months	82 years 6 months
Industrial Property [Member] | Rantoul, Illinois [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	41,277
Land and Land Estate	1,304
Building and Improvements	32,562
Lease in-place Value	7,411
Industrial Property [Member] | Lewisburg, Tennessee [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	13,320
Land and Land Estate	173
Building and Improvements	10,865
Lease in-place Value	2,282
Industrial Property [Member] | North Las Vegas, Nevada [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	28,249
Land and Land Estate	3,244
Building and Improvements	21,444
Lease in-place Value	3,561
Industrial Property [Member] | Bingen, Washington [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	20,391
Land and Land Estate	0
Building and Improvements	18,075
Lease in-place Value	2,316
Industrial Property [Member] | Anniston, Alabama [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	20,907
Land and Land Estate	1,201
Building and Improvements	16,771
Lease in-place Value	2,935
Industrial Property [Member] | Long Island City, New York [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		42,124
Land and Land Estate		0
Building and Improvements		42,124
Above Market Lease Value		0
Lease in-place Value		0
Industrial Property [Member] | Houston, Texas [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		81,400
Land and Land Estate		15,055
Building and Improvements		57,949
Above Market Lease Value		0
Lease in-place Value		8,396
Office Property [Member] | Parachute, Colorado [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	13,928
Land and Land Estate	1,400
Building and Improvements	10,751
Lease in-place Value	1,777
Office Property [Member] | Rock Hill, South Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	24,715
Land and Land Estate	1,601
Building and Improvements	18,989
Lease in-place Value	4,125
Office Property [Member] | Denver, Colorado [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		34,547	[1]
Land and Land Estate		2,207	[1]
Building and Improvements		26,724	[1]
Above Market Lease Value		0	[1]
Lease in-place Value		5,616	[1]
Payments for tenant improvements		3,825
Office Property [Member] | Other Locations [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		13,144	[2]
Land and Land Estate		1,522	[2]
Building and Improvements		10,374	[2]
Above Market Lease Value		0	[2]
Lease in-place Value		1,248	[2]
Construction in progress		1,969
Office Property [Member] | Omaha, Nebraska [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		39,125
Land and Land Estate		2,058
Building and Improvements		32,343
Above Market Lease Value		0
Lease in-place Value		4,724
Retail Site [Member] | Tuscaloosa, Alabama [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		8,397	[3]
Land and Land Estate		2,793	[3]
Building and Improvements		5,604	[3]
Above Market Lease Value		0	[3]
Lease in-place Value		0	[3]
Payments for leasing costs		323
Retail Site [Member] | Albany, Georgia [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		7,074	[4]
Land and Land Estate		1,468	[4]
Building and Improvements		5,606	[4]
Above Market Lease Value		0	[4]
Lease in-place Value		0	[4]
Payments for leasing costs		338
Land [Member] | New York, New York [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	30,426	302,000	[5]
Land and Land Estate	22,000	224,935	[5]
Building and Improvements	0	0	[5]
Above Market Lease Value		0	[5]
Lease in-place Value	8,426	77,065	[5]
Number of real estate properties	3
Land [Member] | Danville, Virginia [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		4,727
Land and Land Estate		3,454
Building and Improvements		0
Above Market Lease Value		673
Lease in-place Value		600
Rehabilitation Hospital [Member] | Vineland, New Jersey [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	19,100
Land and Land Estate	2,698
Building and Improvements	12,790
Lease in-place Value	$ 3,612

[1] The Company incurred additional tenant related costs of $3,825.

[2] Includes four properties. One property was under construction at December 31, 2013, $1,969 of construction in progress costs are included in building and improvements above.

[3] The Company incurred leasing costs of $323. The property was sold in September 2013.

[4] The Company incurred leasing costs of $338.

[5] Includes three properties.