Derivatives (Fair Values of Derivative Financial Instruments) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		$ 6,010,689	$ 4,301,969
Fair Values, Assets		23	3,325
Less: netting adjustment, Assets	[1],[2]	(27,056)	(11,979)
Fair Values, Liabilities		11,953	2,160
Less: netting adjustment, Liabilities	[1],[2]	(43,914)	(22,588)
Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	81,502	28,959
Total derivate assets/liabilities	[1]	54,446	16,980
Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Total derivate assets/liabilities	[1]	21,089	22,227
Fair Values, Liabilities	[1]	65,003	44,815
Derivatives Designated as Hedging Instruments [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		1,659,400	1,358,110
Derivatives Designated as Hedging Instruments [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	25,646	3,954
Derivatives Designated as Hedging Instruments [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	2,105	11,262
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		4,351,289	2,943,859
Derivatives Not Designated as Hedging Instruments [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	55,856	25,005
Derivatives Not Designated as Hedging Instruments [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	62,898	33,553
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		3,759,232	2,554,808
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	54,512	23,670
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	55,664	24,669
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		254,825	171,222
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	21	10
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	45	131
Derivatives Not Designated as Hedging Instruments [Member] | Forward Commitments to Sell Residential Mortgage Loans [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		145,623	77,208
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]	651	110
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]	744	664
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		83,224	59,119
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]	369	464
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]	375	67
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Forward Contracts [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		64,632	37,749
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Forward Contracts [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Fair Values, Assets	[1]	303	751
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Forward Contracts [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	366	718
Derivatives Not Designated as Hedging Instruments [Member] | Visa Class B derivative contract [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		43,753	43,753
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]	5,704	7,304
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		1,175,000	875,000
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]	24,172	3,954
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]	337	9,173
Fair Value Hedging [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Securities [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		441,400
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]	1,474
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]	1,759
Fair Value Hedging [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Brokered Deposits [Member]
Derivatives Fair Value [Line Items]
Notional or Contractual Amount		43,000	483,110
Fair Value Hedging [Member] | Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps - Brokered Deposits [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair Values, Liabilities	[1]	$ 9	$ 2,089

[1] Derivative assets and liabilities are reported 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.