Derivatives (Fair Values of Derivative Financial Instruments) (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2022	Dec. 31, 2021
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		$ 8,684,485	$ 8,649,657
Fair Values, Assets		45,281	6,908
Less: netting adjustment	[1],[2]	(88,275)	(30,304)
Fair Values, Liabilities		3,796	22,244
Less: netting adjustment	[1],[2]	(45,705)	(61,534)
Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	147,933	106,171
Total derivative assets/liabilities	[1]	59,658	75,867
Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Total derivative assets/liabilities	[1]	78,257	35,046
Fair Values, Liabilities	[1]	123,962	96,580
Derivatives Designated as Hedging Instruments [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		3,019,650	2,962,650
Derivatives Designated as Hedging Instruments [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	62,029	28,022
Derivatives Designated as Hedging Instruments [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	36,930	15,111
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		5,664,835	5,687,007
Derivatives Not Designated as Hedging Instruments [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	85,904	78,149
Derivatives Not Designated as Hedging Instruments [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	87,032	81,469
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		5,188,151	5,193,991
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	84,071	75,819
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	82,835	75,861
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		235,301	217,437
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	5	11
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	16	35
Derivatives Not Designated as Hedging Instruments [Member] | Forward Commitments to Sell Residential Mortgage Loans [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		31,306	46,739
Derivatives Not Designated as Hedging Instruments [Member] | Forward Commitments to Sell Residential Mortgage Loans [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	55	1
Derivatives Not Designated as Hedging Instruments [Member] | Forward Commitments to Sell Residential Mortgage Loans [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	168	645
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate-Lock Commitments on Residential Mortgage Loans [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		66,675	82,037
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate-Lock Commitments on Residential Mortgage Loans [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	585	1,525
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate-Lock Commitments on Residential Mortgage Loans [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	132	1
Derivatives Not Designated as Hedging Instruments [Member] | To Be Announced (TBA) Securities [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		42,750	55,000
Derivatives Not Designated as Hedging Instruments [Member] | To Be Announced (TBA) Securities [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	736	15
Derivatives Not Designated as Hedging Instruments [Member] | To Be Announced (TBA) Securities [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	7	53
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Forward Contracts [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		57,213	48,364
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Forward Contracts [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	452	778
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Forward Contracts [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	358	758
Derivatives Not Designated as Hedging Instruments [Member] | Visa Class B derivative contract [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		43,439	43,439
Derivatives Not Designated as Hedging Instruments [Member] | Visa Class B derivative contract [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	3,516	4,116
Cash Flow Hedge [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Variable Rate Loans [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		1,325,000	1,125,000
Cash Flow Hedge [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Variable Rate Loans [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	1,336	5,884
Cash Flow Hedge [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Variable Rate Loans [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	36,930	4,421
Cash Flow Hedge [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		100,000
Fair Value Hedging [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Securities [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		1,694,650	1,837,650
Fair Value Hedging [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Securities [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	$ 60,693	22,138
Fair Value Hedging [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Securities [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]		$ 10,690

[1] Derivative assets and liabilities are reported at fair value in other assets or other liabilities, respectively, in the consolidated balance sheets.

[2] Represents balance sheet netting of derivative assets and liabilities for variation margin collateral held or placed with the same central clearing counterparty. See offsetting assets and liabilities for further information.