Derivatives and Hedging Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jun. 16, 2016
Derivative [Line Items]
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	$ 38,500,000	$ 85,500,000
Derivative Asset, Fair Value, Gross Asset	38,400,000	3,300,000	$ 1,800,000
Derivative Liability, Fair Value, Gross Liability	96,300,000	86,100,000	55,500,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	10,000,000.0	2,700,000	1,800,000
Derivative Netting Adjustments, Assets	(28,400,000)	(600,000)	0
Derivative Asset, Collateral, Obligation to Return Cash, Offset	1,200,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	(67,900,000)	(85,500,000)	(55,500,000)
Derivative Netting Adjustments, Liabilities	28,400,000	600,000	0
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	(6,500,000)
Derivative Asset, Not Subject to Master Netting Arrangement	11,800,000	900,000	100,000
Derivative Liability, Not Subject to Master Netting Arrangement	(3,500,000)	(1,400,000)	(100,000)
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	50,200,000	4,200,000	1,900,000
Derivative Asset, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election	21,800,000	3,600,000	1,900,000
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(99,800,000)	(87,500,000)	(55,600,000)
Derivative Liability, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election	(71,400,000)	(86,900,000)	(55,600,000)
Derivative, Collateral, Right to Reclaim Securities	67,100,000	117,800,000	52,500,000
Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	49,800,000
Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	28,400,000
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	13,800,000	3,300,000	1,800,000
Derivative Liability, Fair Value, Gross Liability	54,500,000	86,100,000	55,500,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	13,800,000	3,300,000	1,800,000
Derivative Netting Adjustments, Assets		0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(54,500,000)	(86,100,000)	(55,500,000)
Derivative Netting Adjustments, Liabilities		0	0
Derivative Asset, Not Subject to Master Netting Arrangement	100,000	200,000	100,000
Derivative Liability, Not Subject to Master Netting Arrangement	(100,000)	(200,000)	(100,000)
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Asset, Not Subject to Master Netting Arrangement	200,000	700,000	0
Derivative Liability, Not Subject to Master Netting Arrangement	(1,400,000)	(1,200,000)	0
Forward purchase contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7,900,000	0	0
Derivative Liability, Fair Value, Gross Liability	17,700,000	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	7,900,000	0	0
Derivative Netting Adjustments, Assets		0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(17,700,000)	0	0
Derivative Netting Adjustments, Liabilities		0	0
Derivative Asset, Not Subject to Master Netting Arrangement	200,000
Derivative Liability, Not Subject to Master Netting Arrangement	(300,000)
Forward sales contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	15,500,000	0	0
Derivative Liability, Fair Value, Gross Liability	17,600,000	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	15,500,000	0	0
Derivative Netting Adjustments, Assets		0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(17,600,000)	0	0
Derivative Netting Adjustments, Liabilities		$ 0	0
Derivative Asset, Not Subject to Master Netting Arrangement	300,000
Derivative Liability, Not Subject to Master Netting Arrangement	(100,000)
Interest Rate Lock Commitments
Derivative [Line Items]
Derivative Asset, Not Subject to Master Netting Arrangement	11,000,000.0
Derivative Liability, Not Subject to Master Netting Arrangement	(1,600,000)
Interest Rate Lock Commitments | Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,000,000.0)
Forward Contracts | Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	52,200,000
Forward Contracts | Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	4,200,000
Other Contract | Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,400,000)
Swaption | Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(300,000)
Future | Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	23,900,000
Subordinated Debentures Maturing July 2025 [Member] | Subordinated Debt [Member]
Derivative [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.44%
Debt Instrument, Face Amount		$ 75,000,000.0
Subordinated Debentures Maturing July 2056 [Member] | Subordinated Debt [Member]
Derivative [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.25%		6.25%
Debt Instrument, Face Amount		$ 175,000,000.0		$ 175,000,000
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	13,800,000	3,300,000	1,800,000
Derivative Liability, Fair Value, Gross Liability	54,500,000	86,100,000	55,500,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	13,800,000	3,300,000	1,800,000
Derivative Liability, Fair Value, Gross Liability	54,500,000	86,100,000	55,500,000
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	35,200,000	900,000	100,000
Derivative Liability, Fair Value, Gross Liability	38,800,000	1,400,000	100,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	100,000	200,000	100,000
Derivative Liability, Fair Value, Gross Liability	100,000	200,000	100,000
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	200,000	700,000	0
Derivative Liability, Fair Value, Gross Liability	1,400,000	1,200,000	0
Not Designated as Hedging Instrument [Member] | Forward purchase contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	8,100,000	0	0
Derivative Liability, Fair Value, Gross Liability	18,000,000.0	0	0
Not Designated as Hedging Instrument [Member] | Forward sales contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	15,800,000	0	0
Derivative Liability, Fair Value, Gross Liability	17,700,000	0	0
Not Designated as Hedging Instrument [Member] | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	11,000,000.0	0	0
Derivative Liability, Fair Value, Gross Liability	$ 1,600,000	$ 0	$ 0