Investments - Schedule of Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Carrying Amount	$ 69,132	$ 66,421
Intangible assets, Accumulated Amortization	15,272	13,642
Intangible assets, Net Carrying Amount	53,860	52,779
Intangible market lease liabilities, Gross Carrying Amount	12,322	14,894
Intangible market lease liabilities, Accumulated Amortization	2,248	3,278
Intangible market lease liabilities, Net Carrying Amount	10,074	11,616
In-place Leases
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Carrying Amount	53,476	50,317
Intangible assets, Accumulated Amortization	10,603	9,498
Intangible assets, Net Carrying Amount	42,873	40,819
Intangible Market Lease Assets
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Carrying Amount	15,656	16,104
Intangible assets, Accumulated Amortization	4,669	4,144
Intangible assets, Net Carrying Amount	$ 10,987	$ 11,960