Derivative Financial Instruments (Schedule fair value of derivative instruments) (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	$ 5,554,015	$ 5,571,385
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	159,117	339,058
Derivative Asset, Fair Value, Amount Offset Against Collateral	6,364	7,748
Asset Derivatives, Fair Value, Less: Cash collateral posted	19,272	33,972
Derivative asset	133,481	297,338
Liability Derivatives, Notional Amount	4,747,534	4,853,650
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	21,784	12,690
Derivative Liability, Fair Value, Amount Offset Against Collateral	6,364	7,748
Liability Derivatives, Fair Value, Less: Cash collateral posted	2,119	4,550
Derivative liability	13,301	392
CME SWAPS MARKETS (CME) [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value, Less: Cash collateral posted	59,900
Cross Currency Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	66,000	80,500
Liability Derivatives, Notional Amount	338,200	338,900
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	25,636	41,774
Derivative Asset, Fair Value, Amount Offset Against Collateral	25,636	41,720
Derivative asset	0	54
Derivative Liability, Fair Value, Gross Liability	8,483	12,352
Derivative Liability, Fair Value, Amount Offset Against Collateral	8,483	12,298
Derivative liability	0	54
Designated as Hedging Instrument [Member] | Interest rate derivatives [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	1,000,000	1,000,000
Derivative Asset, Fair Value, Gross Asset	17,583	40,854
Liability Derivatives, Notional Amount	0	25,000
Derivative Liability, Fair Value, Gross Liability	0	110
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	4,554,015	4,571,385
Asset Derivatives, Fair Value, Positions not subject to master netting agreement	141,534	298,204
Liability Derivatives, Notional Amount	4,747,534	4,828,650
Liability Derivatives, Fair Value, Positions not subject to master netting agreement	21,784	12,580
Not Designated as Hedging Instrument [Member] | Interest rate derivatives [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	4,463,048	4,421,627
Derivative Asset, Fair Value, Gross Asset	141,243	297,085
Liability Derivatives, Notional Amount	4,372,846	4,468,153
Derivative Liability, Fair Value, Gross Liability	21,570	12,203
Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member] | RPA-Out [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	14,212	40,771
Derivative Asset, Fair Value, Gross Asset	80	855
Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member] | RPA-In [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Notional Amount	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument [Member] | Other Contract [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	76,755	108,987
Derivative Asset, Fair Value, Gross Asset	211	264
Liability Derivatives, Notional Amount	374,688	360,497
Derivative Liability, Fair Value, Gross Liability	214	377
Not Designated as Hedging Instrument [Member] | CME SWAPS MARKETS (CME) [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Notional Amounts	400,000	100,000
Liability Derivatives, Notional Amount	2,600,000	$ 3,200,000
Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Other Commitment	$ 1,000