Derivatives and Hedging Activities - Narrative (Details) € in Millions, £ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020 USD ($) derivative	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($) derivative	Sep. 30, 2018 USD ($) derivative	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 EUR (€)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2019 EUR (€)	Sep. 30, 2018 GBP (£)
Derivative Instruments, Gain (Loss) [Line Items]
Gains for accelerated reclassification of amounts in other comprehensive income to earnings		$ 2,151
Losses for accelerated reclassification of amounts in other comprehensive income to earnings						$ 24,449
Loss to be reclassified from other comprehensive income					$ 6,700,000
Accumulated other comprehensive (loss) income								$ 5,421,000	$ (20,195,000)
Gains (losses) on derivative instruments	$ (317,000)	1,390,000			2,826,000	1,630,000
Fair value of derivatives in net liability position								18,400,000
Multi-Property Loan, France | Interest rate swaps, net
Derivative Instruments, Gain (Loss) [Line Items]
Derivative asset, notional amount | €							€ 14.5
Payment to settle derivatives	100,000
Multi-Property Loan, Finland
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss recognized in accumulated other comprehensive income (loss) from derivatives (effective portion)			$ 700,000
Amount of loss reclassified from accumulated other comprehensive income (loss) into income as interest expense (effective portion)	$ 100,000				200,000
Accumulated other comprehensive (loss) income								100,000
Multi-Property Loan, Finland | Interest rate swaps, net
Derivative Instruments, Gain (Loss) [Line Items]
Number interest rates swaps terminated | derivative	2		5
Derivative asset, notional amount | €										€ 57.4
Payment to settle derivatives			$ 800,000
Multi-Property GBP Loan
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss reclassified from accumulated other comprehensive income (loss) into income as interest expense (effective portion)	$ 100,000				200,000
Accumulated other comprehensive (loss) income				$ 1,200,000				$ 100,000
Multi-Property GBP Loan | Interest rate swaps, net
Derivative Instruments, Gain (Loss) [Line Items]
Number interest rates swaps terminated | derivative				15
Derivative asset, notional amount | £											£ 208.8
Multi-Property GBP Loan | Interest Rate Floor
Derivative Instruments, Gain (Loss) [Line Items]
Number interest rates swaps terminated | derivative				1
Derivative asset, notional amount | £											£ 28.1
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	$ (300,000)	$ 1,400,000			$ 2,800,000	$ 1,700,000