Derivative and Hedging Activities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Derivatives	$ (5,900)	$ 3,600
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	200
Unrealized Gain on cash flow hedging activities	(5,938)	$ 3,601
Interest Rate Derivative Liabilities, at Fair Value	13,400		$ 7,400
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	400
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Derivative Assets, at Fair Value	0		0
Interest Rate Derivative Liabilities, at Fair Value	13,400		7,400
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 300,000		$ 400,000
Number of Interest Rate Derivatives Held	2