Fair Value Of Assets And Liabilities (Schedule Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	$ 1,649,470	$ 1,416,345
Loans held-for-sale (elected fair value)	18,940	20,881
Securities available-for-sale		5,170,255
Level 3 | Derivatives, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other liabilities	9,425	5,645
Recurring
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale (elected fair value)	18,940	20,881
Securities available-for-sale	4,724,411	4,931,402
Total other assets	189,259	121,456
Total assets	6,582,080	6,490,084
Total other liabilities	135,349	85,061
Total liabilities	879,070	723,576
Recurring | Deferred compensation mutual funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	40,068	39,822
Recurring | Derivatives, forwards and futures
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	19,127	10,161
Total other liabilities	18,738	9,535
Recurring | Derivatives, interest rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	102,766	71,473
Total other liabilities	107,179	69,842
Recurring | Derivatives, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	163
Total other liabilities	9,432	5,684
Recurring | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	98	99
Recurring | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	2,494,300	2,577,376
Recurring | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	2,107,580	2,269,858
Recurring | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	54,402
Recurring | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	6,406
Recurring | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	55,838	55,782
Recurring | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale		27,017
Total other assets	27,135
Recurring | Interest-only strips (elected fair value)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	5,787	1,270
Recurring | Trading securities—fixed income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	1,647,746	1,414,194
Total trading liabilities—fixed income	743,721	638,515
Recurring | Trading securities—fixed income | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	53,315	128,995
Total trading liabilities—fixed income	520,463	506,679
Recurring | Trading securities—fixed income | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	185,118	227,038
Recurring | Trading securities—fixed income | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	305,125	275,014
Recurring | Trading securities—fixed income | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	111,516	54,699
Total trading liabilities—fixed income	329
Recurring | Trading securities—fixed income | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	89,629	34,573
Total trading liabilities—fixed income	2,572
Recurring | Trading securities—fixed income | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	902,580	693,877
Total trading liabilities—fixed income	220,357	131,836
Recurring | Trading securities—fixed income | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	463	(2)
Recurring | Trading securities—mortgage banking
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	1,724	2,151
Recurring | Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale (elected fair value)	0	0
Securities available-for-sale	0	27,017
Total other assets	86,330	49,983
Total assets	86,330	77,000
Total other liabilities	18,738	9,535
Total liabilities	18,738	9,535
Recurring | Level 1 | Deferred compensation mutual funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	40,068	39,822
Recurring | Level 1 | Derivatives, forwards and futures
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	19,127	10,161
Total other liabilities	18,738	9,535
Recurring | Level 1 | Derivatives, interest rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Recurring | Level 1 | Derivatives, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0
Total other liabilities	0	0
Recurring | Level 1 | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 1 | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 1 | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 1 | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0
Recurring | Level 1 | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0
Recurring | Level 1 | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 1 | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale		27,017
Total other assets	27,135
Recurring | Level 1 | Interest-only strips (elected fair value)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 1 | Trading securities—fixed income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0	0
Recurring | Level 1 | Trading securities—fixed income | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0	0
Recurring | Level 1 | Trading securities—fixed income | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 1 | Trading securities—fixed income | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 1 | Trading securities—fixed income | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0
Recurring | Level 1 | Trading securities—fixed income | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0
Recurring | Level 1 | Trading securities—fixed income | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0	0
Recurring | Level 1 | Trading securities—fixed income | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 1 | Trading securities—mortgage banking
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale (elected fair value)	2,222	1,955
Securities available-for-sale	4,718,624	4,903,115
Total other assets	102,929	71,473
Total assets	6,471,521	6,390,737
Total other liabilities	107,186	69,881
Total liabilities	850,907	708,396
Recurring | Level 2 | Deferred compensation mutual funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Recurring | Level 2 | Derivatives, forwards and futures
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Recurring | Level 2 | Derivatives, interest rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	102,766	71,473
Total other liabilities	107,179	69,842
Recurring | Level 2 | Derivatives, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	163
Total other liabilities	7	39
Recurring | Level 2 | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	98	99
Recurring | Level 2 | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	2,494,300	2,577,376
Recurring | Level 2 | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	2,107,580	2,269,858
Recurring | Level 2 | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	54,402
Recurring | Level 2 | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	6,406
Recurring | Level 2 | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	55,838	55,782
Recurring | Level 2 | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale		0
Total other assets	0
Recurring | Level 2 | Interest-only strips (elected fair value)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 2 | Trading securities—fixed income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	1,647,746	1,414,194
Total trading liabilities—fixed income	743,721	638,515
Recurring | Level 2 | Trading securities—fixed income | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	53,315	128,995
Total trading liabilities—fixed income	520,463	506,679
Recurring | Level 2 | Trading securities—fixed income | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	185,118	227,038
Recurring | Level 2 | Trading securities—fixed income | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	305,125	275,014
Recurring | Level 2 | Trading securities—fixed income | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	111,516	54,699
Total trading liabilities—fixed income	329
Recurring | Level 2 | Trading securities—fixed income | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	89,629	34,573
Total trading liabilities—fixed income	2,572
Recurring | Level 2 | Trading securities—fixed income | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	902,580	693,877
Total trading liabilities—fixed income	220,357	131,836
Recurring | Level 2 | Trading securities—fixed income | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	463	(2)
Recurring | Level 2 | Trading securities—mortgage banking
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans held-for-sale (elected fair value)	16,718	18,926
Securities available-for-sale	5,787	1,270
Total other assets	0	0
Total assets	24,229	22,347
Total other liabilities	9,425	5,645
Total liabilities	9,425	5,645
Recurring | Level 3 | Deferred compensation mutual funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Recurring | Level 3 | Derivatives, forwards and futures
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Recurring | Level 3 | Derivatives, interest rate contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0	0
Total other liabilities	0	0
Recurring | Level 3 | Derivatives, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total other assets	0
Total other liabilities	9,425	5,645
Recurring | Level 3 | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 3 | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 3 | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 3 | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0
Recurring | Level 3 | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0
Recurring | Level 3 | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	0	0
Recurring | Level 3 | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale		0
Total other assets	0
Recurring | Level 3 | Interest-only strips (elected fair value)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Securities available-for-sale	5,787	1,270
Recurring | Level 3 | Trading securities—fixed income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0	0
Recurring | Level 3 | Trading securities—fixed income | U.S. treasuries
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0	0
Recurring | Level 3 | Trading securities—fixed income | Government agency issued MBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 3 | Trading securities—fixed income | Government agency issued CMO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 3 | Trading securities—fixed income | Other U.S. government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0
Recurring | Level 3 | Trading securities—fixed income | States and municipalities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0
Recurring | Level 3 | Trading securities—fixed income | Corporates and other debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Total trading liabilities—fixed income	0	0
Recurring | Level 3 | Trading securities—fixed income | Equity, mutual funds, and other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	0	0
Recurring | Level 3 | Trading securities—mortgage banking
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Trading securities	$ 1,724	$ 2,151