Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 284,147	$ 327,440
Overnight investments	1,640,264	797,406
Investment securities held to maturity	2,218,048	2,184,653
Investment in marketable equity securities	111,489	92,599
Loans held for sale	52,837	45,505
Loans and Leases Receivable, Net Amount	26,501,654	25,299,564
Income earned not collected	115,303	109,903
Mortgage servicing rights	20,665	20,647
Deposits	32,719,671	30,672,460
Securities sold under customer repurchase agreements	544,527	543,936
Federal Home Loan Bank borrowings	197,131	193,556
FDIC shared-loss payable	108,892	105,618
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	284,147	327,440
Overnight investments	1,640,264	797,406
Debt Securities, Available-for-sale	4,366,041	4,557,110
Investment securities held to maturity	2,218,048	2,184,653
Investment in marketable equity securities	111,489	92,599
Loans held for sale	52,837	45,505
Loans and Leases Receivable, Net Amount	26,501,654	25,299,564
Income earned not collected	115,303	109,903
Stock issued by Federal Home Loan Bank	25,545	25,304
Mortgage servicing rights	22,809	24,066
Deposits	32,719,671	30,672,460
Securities sold under customer repurchase agreements	544,527	543,936
Federal Home Loan Bank borrowings	197,131	193,556
Short-term borrowings	154,277	140,741
Long-term obligations	18,446	13,921
FDIC shared-loss payable	108,892	105,618
Accrued interest payable	14,197	3,712
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	284,147	327,440
Overnight investments	1,640,264	797,406
Debt Securities, Available-for-sale	4,366,041	4,557,110
Investment securities held to maturity	2,285,283	2,201,502
Investment in marketable equity securities	111,489	92,599
Loans held for sale	52,837	45,505
Loans and Leases Receivable, Net Amount	26,791,041	24,845,060
Income earned not collected	115,303	109,903
Stock issued by Federal Home Loan Bank	25,545	25,304
Mortgage servicing rights	25,129	27,435
Deposits	31,461,196	30,623,214
Securities sold under customer repurchase agreements	544,527	543,936
Federal Home Loan Bank borrowings	203,464	195,374
Short-term borrowings	166,374	151,670
Long-term obligations	18,625	13,985
FDIC shared-loss payable	111,298	105,846
Accrued interest payable	$ 14,197	$ 3,712

Payable to FDIC for Loss Share Agreements

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For an unclassified balance sheet, the amount of fees and other revenue, excluding investment income receivable, earned but not yet received, which were recognized in conformity with revenue recognition criteria based on estimates or specific contractual terms.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

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