Commitments and Contingencies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) contract swap	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Commitments And Contingencies [Line Items]
Aggregate fair value of net liability position	$ 17,200
Derivatives designated as hedging instruments
Commitments And Contingencies [Line Items]
Notional Amount	187,281	$ 339,536
Derivatives not designated as hedging instruments:
Commitments And Contingencies [Line Items]
Notional Amount	4,255,866	3,495,825
Interest rate swaps
Commitments And Contingencies [Line Items]
Accumulated net after-tax losses related to effective cash flow hedges	3,700	4,000
Reclassified to interest expense	2,300
Interest rate swaps | Derivatives not designated as hedging instruments:
Commitments And Contingencies [Line Items]
Notional Amount	$ 4,113,106	3,390,578
Number of derivative instruments | swap	23
Cash flow hedge | Interest rate swaps | Derivatives designated as hedging instruments | Interest Rate Swaps Due Between November 2019 And November 2020
Commitments And Contingencies [Line Items]
Number of derivative contracts held (in contract) | contract	1
Notional amount of derivative asset	$ 75,000
Fixed interest rate	2.97%
Cash flow hedge | Interest rate swaps | Derivatives designated as hedging instruments | Interest Rate Swaps Due Between March 2019 And September 2020
Commitments And Contingencies [Line Items]
Number of derivative contracts held (in contract) | contract	2
Cash flow hedge | Interest rate swap 1 | Derivatives designated as hedging instruments | Interest Rate Swaps Due Between March 2019 And September 2020
Commitments And Contingencies [Line Items]
Notional amount of derivative asset	$ 50,000
Fixed interest rate	2.87%
Cash flow hedge | Interest rate swap 2 | Derivatives designated as hedging instruments | Interest Rate Swaps Due Between March 2019 And September 2020
Commitments And Contingencies [Line Items]
Notional amount of derivative asset	$ 55,000
Fixed interest rate	2.88%
Fair value hedge | Interest rate swaps | Derivatives designated as hedging instruments
Commitments And Contingencies [Line Items]
Number of derivative contracts held (in contract) | contract	1
Notional Amount	$ 7,281	7,536
Fair value hedge | Interest rate swaps | Derivatives not designated as hedging instruments:
Commitments And Contingencies [Line Items]
Notional Amount	$ 10,400
Number of derivative instruments | swap	1
Risk Participation | Interest rate swaps | Derivatives not designated as hedging instruments:
Commitments And Contingencies [Line Items]
Notional Amount	$ 152,900
Non-interest income | Fair value hedge | Interest rate swaps
Commitments And Contingencies [Line Items]
Fee income	$ 33,400	$ 16,400	$ 8,300