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Fair Value Accounting and Measurement (Carrying Amounts and Estimated Fair Values of Selected Financial Instruments) (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Assets |  |
Interest-earning deposits with banks | $ 39,169 | $ 97,918
Debt Securities, Available-for-sale | 2,646,208 | 2,737,751
Equity Securities, FV-NI | 4,963 | 5,080
Estimate of Fair Value Measurement [Member] |  |
Assets |  |
Cash and due from banks | 224,370 | 244,615
Interest-earning deposits with banks | 39,169 | 97,918
Debt Securities, Available-for-sale | 2,646,208 | 2,737,751
Equity Securities, FV-NI | 4,963 | 5,080
FHLB stock | 13,960 | 10,440
Loans held for sale | 6,773 | 5,766
Loans | 8,381,155 | 8,055,817
Interest rate contracts | 8,624 | 6,707
Liabilities |  |
Deposits | 442,561 | 10,524,135
FHLB Advances | 100,102 | 12,281
Repurchase agreements | 46,229 | 79,070
Interest rate contracts | 8,624 | 6,714
Subordinated Debt Obligations, Fair Value Disclosure | 34,986 | 35,895
Junior subordinated debentures, fair value disclosure |  | 8,248
Reported Value Measurement [Member] |  |
Assets |  |
Cash and due from banks | 224,370 | 244,615
Interest-earning deposits with banks | 39,169 | 97,918
Debt Securities, Available-for-sale | 2,646,208 | 2,737,751
Equity Securities, FV-NI | 4,963 | 5,080
FHLB stock | 13,960 | 10,440
Loans held for sale | 6,773 | 5,766
Loans | 8,373,957 | 8,283,011
Interest rate contracts | 8,624 | 6,707
Liabilities |  |
Deposits | 450,602 | 10,532,085
FHLB Advances | 99,549 | 11,579
Repurchase agreements | 46,229 | 79,059
Interest rate contracts | 8,624 | 6,714
Subordinated Debt Obligations, Fair Value Disclosure | 35,555 | 35,647
Junior subordinated debentures, fair value disclosure |  | 8,248
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value Measurement [Member] |  |
Assets |  |
Cash and due from banks | 224,370 | 244,615
Interest-earning deposits with banks | 39,169 | 97,918
Debt Securities, Available-for-sale | 247 | 248
Equity Securities, FV-NI | 4,963 | 5,080
FHLB stock | 0 | 0
Loans held for sale | 0 | 0
Loans | 0 | 0
Interest rate contracts | 0 | 0
Liabilities |  |
Deposits | 0 | 10,041,040
FHLB Advances | 0 | 0
Repurchase agreements | 0 | 0
Interest rate contracts | 0 | 0
Subordinated Debt Obligations, Fair Value Disclosure | 0 | 0
Junior subordinated debentures, fair value disclosure |  | 0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value Measurement [Member] |  |
Assets |  |
Cash and due from banks | 0 | 0
Interest-earning deposits with banks | 0 | 0
Debt Securities, Available-for-sale | 2,645,961 | 2,737,503
Equity Securities, FV-NI | 0 | 0
FHLB stock | 13,960 | 10,440
Loans held for sale | 6,773 | 5,766
Loans | 0 | 0
Interest rate contracts | 8,624 | 6,707
Liabilities |  |
Deposits | 442,561 | 483,095
FHLB Advances | 100,102 | 12,281
Repurchase agreements | 46,229 | 79,070
Interest rate contracts | 8,624 | 6,714
Subordinated Debt Obligations, Fair Value Disclosure | 34,986 | 35,895
Junior subordinated debentures, fair value disclosure |  | 8,248
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value Measurement [Member] |  |
Assets |  |
Cash and due from banks | 0 | 0
Interest-earning deposits with banks | 0 | 0
Debt Securities, Available-for-sale | 0 | 0
Equity Securities, FV-NI | 0 | 0
FHLB stock | 0 | 0
Loans held for sale | 0 | 0
Loans | 8,381,155 | 8,055,817
Interest rate contracts | 0 | 0
Liabilities |  |
Deposits | 0 | 0
FHLB Advances | 0 | 0
Repurchase agreements | 0 | 0
Interest rate contracts | 0 | 0
Subordinated Debt Obligations, Fair Value Disclosure | $ 0 | 0
Junior subordinated debentures, fair value disclosure |  | $ 0

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- Definition Fair value portion of borrowing from Federal Home Loan Bank (FHLBank). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.13(3)(a)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=73530178&loc=d3e59706-112781 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.2) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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