Summary of Significant Accounting Policies - Nature of Operations (Details)	12 Months Ended
	Dec. 31, 2016 a state loan property	Feb. 10, 2017 a	Dec. 31, 2014 a
Description of Business [Line Items]
Number of real estate properties | property	31
Number of states in which entity operates | state	10
Number of commercial mortgage loan investments | loan	3
Fixed Rate Commercial Mortgage [Member]
Description of Business [Line Items]
Number of commercial mortgage loan investments | loan	1
Adjustable Rate Commercial Mortgage [Member]
Description of Business [Line Items]
Number of commercial mortgage loan investments | loan	1
Single-tenant
Description of Business [Line Items]
Number of real estate properties | property	21
Multi-tenant
Description of Business [Line Items]
Number of real estate properties | property	10
Land [Member]
Description of Business [Line Items]
Area of real estate property	9,800		99.7
Subsequent Event [Member]
Description of Business [Line Items]
Area of real estate property		2,210
Subsequent Event [Member] | Single-tenant
Description of Business [Line Items]
Area of real estate property		194
Subsequent Event [Member] | Land [Member]
Description of Business [Line Items]
Area of real estate property		8,200