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Securities (Securities Available for Sale) (Details) - USD ($) $ in Thousands | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | $ 3,210,615 | $ 2,763,321
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 12,799 | 8,480
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | (55,966) | (34,050)
Securities available for sale | 3,167,448 | 2,737,751
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 2,222,521 | 1,752,236
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 9,236 | 1,815
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | (43,467) | (27,326)
Securities available for sale | 2,188,290 | 1,726,725
State and Municipal Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 579,755 | 593,940
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 2,328 | 6,023
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | (7,760) | (3,959)
Securities available for sale | 574,323 | 596,004
U.S. Government Agency and Government-Sponsored Enterprise Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 408,088 | 416,894
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 1,235 | 642
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | (4,736) | (2,762)
Securities available for sale | 404,587 | 414,774
US Government Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 251 | 251
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0 | 0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | (3) | (3)
Securities available for sale | $ 248 | $ 248

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- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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 and equity securities classified as available-for-sale. + References No definition available. + Details
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- Definition This item represents the cost of debt and equity 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 No definition available. + Details
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