Derivative Instruments and Hedging Activities - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) swap	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) swap	Jun. 30, 2017 USD ($)	May 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Number of credit swaps | swap	13		13
Derivative instrument not designated as hedging instruments, liability	$ 14,300		$ 14,300
Aggregate fair value of net liability position	2,100		2,100
CME
Derivative [Line Items]
Collateral posted with counterparties, net of CME variation margin	4,400		4,400
Interest rate swaps
Derivative [Line Items]
Accumulated net after-tax losses related to effective cash flow hedges	4,300		4,300			$ 8,300
Estimated amount of interest rate derivatives to be reclassified to interest expense			1,700
Cash flow hedge | Interest rate swaps | CME
Derivative [Line Items]
CME variation margins	15,900		15,900
Derivatives designated as hedging instruments
Derivative [Line Items]
Aggregate notional amount of derivative asset					$ 125,000
Derivatives designated as hedging instruments | Cash flow hedge | Interest rate swaps | CME
Derivative [Line Items]
CME variation margins	796		796			9,500
Derivatives not designated as hedging instruments
Derivative [Line Items]
Aggregate notional amount of derivative asset	73,400		73,400
Derivatives not designated as hedging instruments | Interest rate swaps | CME
Derivative [Line Items]
CME variation margins	8,200		8,200			$ 951
Noninterest Income | Fair value hedge | Interest rate swaps
Derivative [Line Items]
Fee income related to derivative interest rate swaps executed with commercial loan customers	$ 4,400	$ 4,100	$ 7,700	$ 4,800