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Securities (Securities Available for Sale) (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2018 | Mar. 31, 2017 | Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds | $ 19,761 | $ 0 |
Securities available-for-sale, amortized cost | 2,683,654 |  | $ 2,763,321
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax | 4,208 |  | 8,480
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax | 63,817 |  | 34,050
Available-for-sale Securities, Debt Securities | 2,624,045 |  | 2,737,751
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Securities available-for-sale, amortized cost | 1,693,149 |  | 1,752,236
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax | 698 |  | 1,815
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax | 48,629 |  | 27,326
Available-for-sale Securities, Debt Securities | 1,645,218 |  | 1,726,725
State and Municipal Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Securities available-for-sale, amortized cost | 588,218 |  | 593,940
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax | 3,467 |  | 6,023
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax | 8,937 |  | 3,959
Available-for-sale Securities, Debt Securities | 582,748 |  | 596,004
U.S. Government and Government-Sponsored Enterprise Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Securities available-for-sale, amortized cost | 402,036 |  | 416,894
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax | 43 |  | 642
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax | 6,247 |  | 2,762
Available-for-sale Securities, Debt Securities | 395,832 |  | 414,774
US Government Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Securities available-for-sale, amortized cost | 251 |  | 251
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax | 0 |  | 0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax | 4 |  | 3
Available-for-sale Securities, Debt Securities | $ 247 |  | $ 248

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- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
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- Definition This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
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