Real Estate - Narrative (Details)		2 Months Ended	3 Months Ended		12 Months Ended	17 Months Ended
	Nov. 02, 2015 USD ($)	Dec. 31, 2015	Mar. 31, 2017 USD ($) ft² state Property building	Mar. 31, 2016 USD ($)	Dec. 31, 2016	Mar. 31, 2017 USD ($) ft² state Property building
Real Estate Properties [Line Items]
Number of properties (property) | Property			26			26
Number of buildings (building) | building			34			34
Number of states (state) | state			16			16
Aggregate purchase price of acquired properties			$ 1,100,000,000			$ 1,100,000,000
Area of real estate property (in sqft) | ft²			7,200,000			7,200,000
Depreciation of building			$ 4,892,000	$ 2,338,000
Amortization expense			$ 5,600,000
Advisory fee, base rate		2.00%	2.00%			2.00%
Estimate of acquisition value (percent)			1.00%
Total acquisition fee	3.85%					3.85%
Advisory fee, contingent percentage	1.85%					1.85%
Amount retained subject to conditions	$ 5,000,000.0		$ 5,000,000			$ 5,000,000
Amortization period for intangible assets			11 years 1 month 6 days		11 years 4 months 24 days
Minimum
Real Estate Properties [Line Items]
As-if-vacant valuation, discount rate (percent)			6.00%
Maximum
Real Estate Properties [Line Items]
As-if-vacant valuation, discount rate (percent)			8.25%
The Allstate Property [Member]
Real Estate Properties [Line Items]
Area of real estate property (in sqft) | ft²			70,300			70,300
Purchase price			$ 14,750,000
Purchase price credit applied at closing			402,000
Purchase price consideration			$ 500,000