Derivative Financial Instruments (Schedule fair value of derivative instruments) (Detail) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	$ 7,499,656,000	$ 5,554,015,000
Asset Derivatives, Fair Value, before netting	107,571,000	159,117,000
Asset Derivatives, Fair Value, Less: Master netting agreements	5,977,000	6,364,000
Asset Derivatives, Fair Value, Less: Cash collateral posted	54,206,000	19,272,000
Total derivative instruments, after netting	47,388,000	133,481,000
Liability Derivatives, Notional Amount	6,506,347,000	4,747,534,000
Liability Derivatives, Fair Value	117,324,000	21,784,000
Liability Derivatives, Fair Value, Less: Master netting agreements	5,977,000	6,364,000
Liability Derivatives, Fair Value, Less: Cash collateral posted	904,000	2,119,000
Total derivative instruments, after netting	110,443,000	13,301,000
CME
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value, Less: Cash collateral posted	83,900,000
Total derivative instruments, after netting	0
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	62,877,000	25,636,000
Asset Derivatives, Fair Value, Less: Master netting agreements	60,183,000	25,636,000
Total derivative instruments, after netting	2,694,000	0
Liability Derivatives, Fair Value	6,881,000	8,483,000
Liability Derivatives, Fair Value, Less: Master netting agreements	6,881,000	8,483,000
Total derivative instruments, after netting	0	0
Designated as Hedging Instrument | Interest rate derivatives
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	1,000,000,000	1,000,000,000
Asset Derivatives, Fair Value	5,651,000	17,583,000
Liability Derivatives, Notional Amount	0	0
Liability Derivatives, Fair Value	0	0
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	6,499,656,000	4,554,015,000
Asset Derivatives, Fair Value, Total	101,920,000	141,534,000
Liability Derivatives, Notional Amount	6,506,347,000	4,747,534,000
Liability Derivatives, Fair Value, Positions not subject to master netting agreement	117,324,000	21,784,000
Not Designated as Hedging Instrument | Interest rate derivatives
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	6,385,652,000	4,463,048,000
Asset Derivatives, Fair Value	101,454,000	141,243,000
Liability Derivatives, Notional Amount	6,054,975,000	4,372,846,000
Liability Derivatives, Fair Value	117,041,000	21,570,000
Not Designated as Hedging Instrument | Mortgage Banking Derivatives | RPA-Out
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	4,123,000	14,212,000
Asset Derivatives, Fair Value	32,000	80,000
Not Designated as Hedging Instrument | Mortgage Banking Derivatives | RPA-In
Derivatives, Fair Value [Line Items]
Liability Derivatives, Notional Amount	336,000	0
Liability Derivatives, Fair Value	1,000	0
Not Designated as Hedging Instrument | Other
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	109,881,000	76,755,000
Asset Derivatives, Fair Value	434,000	211,000
Liability Derivatives, Notional Amount	451,036,000	374,688,000
Liability Derivatives, Fair Value	282,000	214,000
Not Designated as Hedging Instrument | Interest Rate Swap, CME
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	2,000,000,000	400,000,000
Liability Derivatives, Notional Amount	1,500,000,000	2,600,000,000
Not Designated as Hedging Instrument | Credit Risk Contract | RPA-Out
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	68,000,000	66,000,000
Not Designated as Hedging Instrument | Credit Risk Contract | RPA-In
Derivatives, Fair Value [Line Items]
Liability Derivatives, Notional Amount	438,800,000	$ 338,200,000
Interest Rate Lock Commitments
Derivatives, Fair Value [Line Items]
Other commitment	$ 900,000