Derivative Instruments and Hedging Activities - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) swap	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Number of credit swaps | swap	11
Derivative instrument not designated as hedging instruments, liability	$ 14,500
Aggregate fair value of net liability position	2,400
CME
Derivative [Line Items]
Collateral posted with counterparties, net of CME variation margin	41,300
Interest rate swaps
Derivative [Line Items]
Accumulated net after-tax losses related to effective cash flow hedges	5,400		$ 8,300
Estimated amount of interest rate derivatives to be reclassified to interest expense	2,600
Derivatives designated as hedging instruments | Cash flow hedge | Interest rate caps and swaps | CME
Derivative [Line Items]
CME variation margins	11,100		9,500
Derivatives not designated as hedging instruments
Derivative [Line Items]
Aggregate notional amount of derivative asset	63,400
Derivatives not designated as hedging instruments | Interest rate swaps | CME
Derivative [Line Items]
CME variation margins	9,900		$ 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	$ 3,300	$ 661