Derivative Instruments and Hedging Activities - Summary of Fair Value of Interest Rate Swaps (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Interest rate swap assets	$ 33,276	$ 9,855
Interest rate swap liabilities		317
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member] | Other Assets [Member]
Derivative [Line Items]
Interest rate swap assets	$ 33,276	9,855
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest rate swap liabilities		$ 317