Derivative Financial Instruments - Fair Value of Derivative Financial Instruments and Their Classification on Balance Sheet (Details) - Interest rate contracts - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives designated as hedging instruments | Other Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 548	$ 18
Derivatives designated as hedging instruments | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	387	1,383
Derivatives not designated as hedging instruments | Other Assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	13,763	7,305
Derivatives not designated as hedging instruments | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 13,763	$ 7,305