Investments in Real Estate and Real Estate Under Construction - Schedule of Acquired Properties (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) building	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	$ 727,581	$ 310,128
Land and Land Estate	31,930	29,085
Building and Improvements	625,933	250,945
Lease in-place Value	72,508	32,113
Below Market Lease	$ (2,790)	$ (2,015)
Leases, Acquired-in-Place [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Weighted-average life of intangible assets (years)	12 years 2 months	16 years 7 months 6 days
Leases, Acquired-in-Place, Market Adjustment [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Weighted-average life of intangible assets (years)	14 years 11 months	16 years 1 month 6 days
Office Property [Member] | Lake Jackson, Texas [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	$ 70,401	$ 78,484
Land and Land Estate	3,078	4,357
Building and Improvements	67,323	74,127
Lease in-place Value	0	0
Below Market Lease	$ 0	0
Number of buildings completed | building	4
Redemption of noncontrolling interests	$ 7,951
Office Property [Member] | Charlotte, North Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	61,339
Land and Land Estate	3,771
Building and Improvements	47,064
Lease in-place Value	10,504
Below Market Lease	0
Industrial Property [Member] | New Century, Kansas [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	12,056
Land and Land Estate	0
Building and Improvements	13,198
Lease in-place Value	1,648
Below Market Lease	(2,790)
Industrial Property [Member] | Lebanon, Indiana [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	36,194
Land and Land Estate	2,100
Building and Improvements	29,443
Lease in-place Value	4,651
Below Market Lease	0
Industrial Property [Member] | Cleveland, Tennessee [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	34,400
Land and Land Estate	1,871
Building and Improvements	29,743
Lease in-place Value	2,786
Below Market Lease	0
Industrial Property [Member] | Grand Prairie, Texas [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	24,317
Land and Land Estate	3,166
Building and Improvements	17,985
Lease in-place Value	3,166
Below Market Lease	0
Industrial Property [Member] | San Antonio, Texas [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	45,507
Land and Land Estate	1,311
Building and Improvements	36,644
Lease in-place Value	7,552
Below Market Lease	0
Industrial Property [Member] | Opelika, Alabama [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	37,269
Land and Land Estate	134
Building and Improvements	33,183
Lease in-place Value	3,952
Below Market Lease	0
Industrial Property [Member] | McDonough, Georgia [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	66,700
Land and Land Estate	5,441
Building and Improvements	52,762
Lease in-place Value	8,497
Below Market Lease	0
Industrial Property [Member] | Byhalia, Mississippi [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	36,590
Land and Land Estate	1,751
Building and Improvements	31,236
Lease in-place Value	3,603
Below Market Lease	0
Industrial Property [Member] | Jackson, Tennessee [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	57,920
Land and Land Estate	1,454
Building and Improvements	49,026
Lease in-place Value	7,440
Below Market Lease	0
Industrial Property [Member] | Smyrna, Tennessee [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	104,890
Land and Land Estate	1,793
Building and Improvements	93,940
Lease in-place Value	9,157
Below Market Lease	0
Industrial Property [Member] | Lafayette, Indiana [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	17,450
Land and Land Estate	662
Building and Improvements	15,578
Lease in-place Value	1,210
Below Market Lease	0
Industrial Property [Member] | Romulus, Michigan [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	38,893
Land and Land Estate	2,438
Building and Improvements	33,786
Lease in-place Value	2,669
Below Market Lease	0
Industrial Property [Member] | Warren, Michigan [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	46,955
Land and Land Estate	972
Building and Improvements	42,521
Lease in-place Value	3,462
Below Market Lease	0
Industrial Property [Member] | Winchester, Virginia [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	36,700
Land and Land Estate	1,988
Building and Improvements	32,501
Lease in-place Value	2,211
Below Market Lease	0
Industrial Property [Member] | Detroit, Michigan [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		29,697
Land and Land Estate		1,133
Building and Improvements		25,009
Lease in-place Value		3,555
Below Market Lease		0
Industrial Property [Member] | Anderson, South Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		61,347
Land and Land Estate		4,663
Building and Improvements		45,011
Lease in-place Value		11,673
Below Market Lease		0
Industrial Property [Member] | Wilsonville, Oregon [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		43,100
Land and Land Estate		6,815
Building and Improvements		32,380
Lease in-place Value		5,920
Below Market Lease		(2,015)
Industrial Property [Member] | Romeoville, Illinois [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		52,700
Land and Land Estate		7,524
Building and Improvements		40,167
Lease in-place Value		5,009
Below Market Lease		0
Industrial Property [Member] | Edwardsville, Illinois [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		44,800
Land and Land Estate		4,593
Building and Improvements		34,251
Lease in-place Value		5,956
Below Market Lease		$ 0
LCIF [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	132,611
Land and Land Estate	7,909
Building and Improvements	107,570
Lease in-place Value	$ 17,132
Weighted-average life of intangible assets (years)	15 years 11 months	14 years 11 months
Redemption of noncontrolling interests	$ 129,990	$ 0	$ 0
LCIF [Member] | Charlotte, North Carolina [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	61,339
Land and Land Estate	3,771
Building and Improvements	47,064
Lease in-place Value	10,504
LCIF [Member] | Warren, Michigan [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	46,955
Land and Land Estate	972
Building and Improvements	42,521
Lease in-place Value	3,462
LCIF [Member] | Romeoville, Illinois [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis		52,700
Land and Land Estate		7,524
Building and Improvements		40,167
Lease in-place Value		$ 5,009
LCIF [Member] | Grand Prairie, TX [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Initial Cost Basis	24,317
Land and Land Estate	3,166
Building and Improvements	17,985
Lease in-place Value	$ 3,166