Derivatives and Hedging Activities (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) Financial_Instrument	Dec. 31, 2015 USD ($)
Derivative [Line Items]
Expected amount of derivative related interest to be reclassified to interest expense over the next 12 months	$ 1,462,000
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivative [Line Items]
Derivative asset	44,000	$ 4,000
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Accounts Payable And Other Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	$ (1,077,000)	(1,943,000)
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Number of derivative instruments held | Financial_Instrument	10
Notional amount of derivatives	$ 505,000,000
Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Interest Expense [Member]
Derivative [Line Items]
Reclassified from AOCI into Income	3,990,000	5,466,000
Amount of loss recognized in OCI on derivatives (effective portion)	(3,084,000)	$ (7,809,000)
Cash Flow Hedging [Member] | Interest Rate Swap, Maturing 2020 [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional amount of derivatives	250,000,000
Cash Flow Hedging [Member] | Interest Rate Swap, Maturing 2021 [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 255,000,000