Derivatives and Hedging Activities (Narrative) (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($) instrument	Dec. 31, 2019 USD ($) instrument	Dec. 31, 2018 USD ($) instrument	Dec. 31, 2017 USD ($)	Nov. 01, 2019 USD ($)
Derivative [Line Items]
Notional Amount					$ 88,700,000
Loss on non-designated derivatives		$ (68,000)	$ (157,000)	$ (198,000)
Derivative, net liability position, aggregate fair value	$ 5,300,000	5,300,000
Aggregate termination value	$ 5,300,000	$ 5,300,000
Designated as Hedging Instrument | Interest rate swaps
Derivative [Line Items]
Number of Instruments | instrument	9	9	2
Number of instruments terminated | instrument	2	2
Notional Amount	$ 578,500,000	$ 578,500,000	$ 250,000,000
Proceeds from sale of interest rate cash flow hedge	2,200,000
Designated as Hedging Instrument | Interest rate contract
Derivative [Line Items]
Cash flow hedge reclassification current	2,100,000
Interest Expense | Designated as Hedging Instrument | Interest rate contract
Derivative [Line Items]
Cash flow hedge reclassification current	100,000
Cash flow hedge reclassification in next twelve months	$ 2,200,000	$ 2,200,000
Capital One MOB Loan | Designated as Hedging Instrument | Interest rate swaps
Derivative [Line Items]
Number of Instruments | instrument	1	1
Notional Amount	$ 250,000,000.0	$ 250,000,000.0
Capital One MOB Loan | Interest Expense | Designated as Hedging Instrument | Interest rate contract
Derivative [Line Items]
Cash flow hedge reclassification current	$ 2,200,000