Investments - Summary of Projected Amortization Expenses for Next Five Years (Details) $ in Thousands	Mar. 31, 2019 USD ($)
In-place Leases | Amortization Expense
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization expense, April 1 - December 31, 2019	$ 3,836
Finite-lived intangible assets, amortization expense, 2020	4,712
Finite-lived intangible assets, amortization expense, 2021	4,515
Finite-lived intangible assets, amortization expense, 2022	4,387
Finite-lived intangible assets, amortization expense, 2023	4,036
Adjustment in-place Lease | Amortization Expense
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization expense, April 1 - December 31, 2019	3,836
Finite-lived intangible assets, amortization expense, 2020	4,712
Finite-lived intangible assets, amortization expense, 2021	4,515
Finite-lived intangible assets, amortization expense, 2022	4,387
Finite-lived intangible assets, amortization expense, 2023	4,036
Above-Market Lease Assets | Rental Revenue
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, amortization expense, Above and below market lease (assets) liabilities net adjustment to rental revenue, April 1 - December 31, 2019	(1,035)
Finite-lived intangible assets, amortization expense, 2020	(1,319)
Finite-lived intangible assets, amortization expense, 2021	(1,300)
Finite-lived intangible assets, amortization expense, 2022	(1,299)
Finite-lived intangible assets, amortization expense, 2023	(1,267)
Below-Market Lease Liabilities | Rental Revenue
Finite Lived Intangible Assets [Line Items]
Below market leases, amortization income, April 1 - December 31, 2019	431
Below market leases, amortization income, 2020	553
Below market leases, amortization income, 2021	553
Below market leases, amortization income, 2022	554
Below market leases, amortization income, 2023	502
Net Adjustment in-place Lease | Rental Revenue
Finite Lived Intangible Assets [Line Items]
Above and below market lease (assets) liabilities net adjustment to rental revenue, April 1 - December 31, 2019	(604)
Above and below market lease (assets) liabilities net adjustment to rental revenue, 2020	(766)
Above and below market lease (assets) liabilities net adjustment to rental revenue, 2021	(747)
Above and below market lease (assets) liabilities net adjustment to rental revenue, 2022	(745)
Above and below market lease (assets) liabilities net adjustment to rental revenue, 2023	$ (765)