Derivative Financial Instruments (Schedule fair value of derivative instruments) (Detail) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	$ 9,408,742,000	$ 11,377,707,000
Asset Derivatives, Fair Value, before netting	363,542,000	330,636,000
Asset Derivatives, Fair Value, Less: Master netting agreements	61,395,000	55,949,000
Asset Derivatives, Fair Value, Less: Cash collateral posted	285,297,000	232,190,000
Total derivative instruments, after netting	16,850,000	42,497,000
Liability Derivatives, Notional Amount	14,037,672,000	11,703,252,000
Liability Derivatives, Fair Value	407,393,000	335,810,000
Liability Derivatives, Fair Value, Less: Master netting agreements	61,395,000	55,949,000
Liability Derivatives, Fair Value, Less: Cash collateral posted	0	0
Total derivative instruments, after netting	345,998,000	279,861,000
CME
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value, Less: Cash collateral posted	2,300,000
Total derivative instruments, after netting	0	0
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	346,853,000	289,778,000
Asset Derivatives, Fair Value, Less: Master netting agreements	61,395,000	55,949,000
Total derivative instruments, after netting	285,297,000	232,190,000
Liability Derivatives, Fair Value	61,395,000	55,949,000
Liability Derivatives, Fair Value, Less: Master netting agreements	61,395,000	55,949,000
Total derivative instruments, after netting	0	0
Designated as Hedging Instrument | Interest rate derivatives
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	500,000,000	2,750,000,000
Asset Derivatives, Fair Value	263,000	11,140,000
Liability Derivatives, Notional Amount	4,750,000,000	2,700,000,000
Liability Derivatives, Fair Value	44,366,000	13,679,000
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	8,908,742,000	8,627,707,000
Asset Derivatives, Fair Value, Total	363,279,000	319,496,000
Liability Derivatives, Notional Amount	9,287,672,000	9,003,252,000
Liability Derivatives, Fair Value, Positions not subject to master netting agreement	363,027,000	322,131,000
Not Designated as Hedging Instrument | Interest rate derivatives
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	8,542,883,000	8,284,356,000
Asset Derivatives, Fair Value	362,602,000	319,122,000
Liability Derivatives, Notional Amount	8,542,895,000	8,272,197,000
Liability Derivatives, Fair Value	362,802,000	321,064,000
Not Designated as Hedging Instrument | Mortgage Banking Derivatives | RPA-Out
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	1,463,000	2,798,000
Asset Derivatives, Fair Value	15,000	37,000
Not Designated as Hedging Instrument | Mortgage Banking Derivatives | RPA-In
Derivatives, Fair Value [Line Items]
Liability Derivatives, Notional Amount	0	0
Liability Derivatives, Fair Value	0	0
Not Designated as Hedging Instrument | Other
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	364,396,000	340,553,000
Asset Derivatives, Fair Value	662,000	337,000
Liability Derivatives, Notional Amount	744,777,000	731,055,000
Liability Derivatives, Fair Value	225,000	1,067,000
Not Designated as Hedging Instrument | Interest Rate Swap, CME
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	91,000,000	113,800,000
Liability Derivatives, Notional Amount	0	0
Not Designated as Hedging Instrument | Credit Risk Contract | RPA-Out
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	300,500,000	299,200,000
Not Designated as Hedging Instrument | Credit Risk Contract | RPA-In
Derivatives, Fair Value [Line Items]
Liability Derivatives, Notional Amount	707,600,000	682,900,000
Interest Rate Lock Commitments
Derivatives, Fair Value [Line Items]
Other commitment	$ 1,700,000	$ 1,000,000