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Securities (Tables) | 9 Months Ended
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Sep. 30, 2019
Debt Securities, Available-for-sale [Abstract] |
Securities Available for Sale | The following table summarizes the amortized cost, gross unrealized gains and losses and the resulting fair value of debt securities available for sale:
|  | Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Fair Value
September 30, 2019 |  | (in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations (1) |  | $ | 2,432,873 |  |  | $ | 61,024 |  |  | $ | (11,062 | ) |  | $ | 2,482,835 |
Other asset-backed securities (1) |  | 166,482 |  |  | 5,149 |  |  | (53 | ) |  | 171,578 |
State and municipal securities |  | 488,273 |  |  | 9,471 |  |  | (430 | ) |  | 497,314 |
U.S. government agency and government-sponsored enterprise securities |  | 212,265 |  |  | 3,382 |  |  | (52 | ) |  | 215,595 |
U.S. government securities |  | 250 |  |  | — |  |  | — |  |  | 250 |
Total |  | $ | 3,300,143 |  |  | $ | 79,026 |  |  | $ | (11,597 | ) |  | $ | 3,367,572 |
December 31, 2018 |  |  |  |  |  |  |  |
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations (1) |  | $ | 2,045,728 |  |  | $ | 8,473 |  |  | $ | (40,846 | ) |  | $ | 2,013,355 |
Other asset-backed securities (1) |  | 176,793 |  |  | 763 |  |  | (2,621 | ) |  | 174,935 |
State and municipal securities |  | 579,755 |  |  | 2,328 |  |  | (7,760 | ) |  | 574,323 |
U.S. government agency and government-sponsored enterprise securities |  | 408,088 |  |  | 1,235 |  |  | (4,736 | ) |  | 404,587 |
U.S. government securities |  | 251 |  |  | — |  |  | (3 | ) |  | 248 |
Total |  | $ | 3,210,615 |  |  | $ | 12,799 |  |  | $ | (55,966 | ) |  | $ | 3,167,448 |
__________ (1) Beginning July 2019, other asset-backed securities were presented separately in this table. Prior period amounts that were previously reported in U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations have been reclassified to conform to current period presentation.
Schedule of gross realized gains and losses on sales and calls of securities available for sale | The following table provides the proceeds and both gross realized gains and losses on sales of debt securities available for sale as well as other securities gains and losses for the periods indicated:
|  | Three Months Ended September 30, |  | Nine Months Ended September 30,
|  | 2019 |  | 2018 |  | 2019 |  | 2018
|  | (in thousands)
Proceeds from sales of debt securities available for sale |  | $ | — |  |  | $ | — |  |  | $ | 259,554 |  |  | $ | 32,330 |
Gross realized gains from sales of debt securities available for sale |  | $ | — |  |  | $ | — |  |  | $ | 3,357 |  |  | $ | 235 |
Gross realized losses from sales of debt securities available for sale |  | — |  |  | — |  |  | (1,225 | ) |  | (129 | )
Other securities losses, net (1) |  | — |  |  | (62 | ) |  | — |  |  | (179 | )
Investment securities gains, net |  | $ | — |  |  | $ | (62 | ) |  | $ | 2,132 |  |  | $ | (73 | )
__________ (1) Other securities losses, net includes net unrealized loss activity associated with equity securities for the periods ended September 30, 2018. There were no sales of equity securities during the periods presented.
Schedule of Contractual Maturities of Investment Securities Available for Sale | The scheduled contractual maturities of debt securities available for sale at September 30, 2019 are presented as follows:
|  | September 30, 2019
|  | Amortized Cost |  | Fair Value
|  | (in thousands)
Due within one year |  | $ | 112,412 |  |  | $ | 112,594 |
Due after one year through five years |  | 412,269 |  |  | 416,294 |
Due after five years through ten years |  | 1,592,778 |  |  | 1,650,631 |
Due after ten years |  | 1,182,684 |  |  | 1,188,053 |
Total debt securities available for sale |  | $ | 3,300,143 |  |  | $ | 3,367,572 |
Carrying Value of Securities Pledged As Collateral | The following table summarizes the carrying value of securities pledged as collateral to secure public funds, borrowings and other purposes as permitted or required by law:
|  | September 30, 2019
|  | (in thousands)
To secure public funds |  | $ | 443,320 |
To secure borrowings |  | 111,421 |
Other securities pledged |  | 155,727 |
Total securities pledged as collateral |  | $ | 710,468 |
Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses | The following table shows the gross unrealized losses and fair value of the Company’s debt securities available for sale with unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at September 30, 2019 and December 31, 2018:
|  | Less than 12 Months |  | 12 Months or More |  | Total
|  | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses
September 30, 2019 |  | (in thousands)
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations (1) |  | $ | 478,690 |  |  | $ | (4,017 | ) |  | $ | 528,228 |  |  | $ | (7,045 | ) |  | $ | 1,006,918 |  |  | $ | (11,062 | )
Other asset-backed securities (1) |  | — |  |  | — |  |  | 6,926 |  |  | (53 | ) |  | 6,926 |  |  | (53 | )
State and municipal securities |  | 52,763 |  |  | (255 | ) |  | 23,237 |  |  | (175 | ) |  | 76,000 |  |  | (430 | )
U.S. government agency and government-sponsored enterprise securities |  | — |  |  | — |  |  | 57,448 |  |  | (52 | ) |  | 57,448 |  |  | (52 | )
U.S. government securities |  | — |  |  | — |  |  | 250 |  |  | — |  |  | 250 |  |  | — |
Total |  | $ | 531,453 |  |  | $ | (4,272 | ) |  | $ | 616,089 |  |  | $ | (7,325 | ) |  | $ | 1,147,542 |  |  | $ | (11,597 | )
December 31, 2018 |  |  |  |  |  |  |  |  |  |  |  |
U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations (1) |  | $ | 114,551 |  |  | $ | (750 | ) |  | $ | 1,207,020 |  |  | $ | (40,096 | ) |  | $ | 1,321,571 |  |  | $ | (40,846 | )
Other asset-backed securities (1) |  | 40,071 |  |  | (222 | ) |  | 94,367 |  |  | (2,399 | ) |  | 134,438 |  |  | (2,621 | )
State and municipal securities |  | 106,292 |  |  | (581 | ) |  | 280,496 |  |  | (7,179 | ) |  | 386,788 |  |  | (7,760 | )
U.S. government agency and government-sponsored enterprise securities |  | 15,392 |  |  | (45 | ) |  | 291,435 |  |  | (4,691 | ) |  | 306,827 |  |  | (4,736 | )
U.S. government securities |  | — |  |  | — |  |  | 247 |  |  | (3 | ) |  | 247 |  |  | (3 | )
Total |  | $ | 276,306 |  |  | $ | (1,598 | ) |  | $ | 1,873,565 |  |  | $ | (54,368 | ) |  | $ | 2,149,871 |  |  | $ | (55,966 | )
__________ (1) Beginning July 2019, other asset-backed securities were presented separately in this table. Prior period amounts that were previously reported in U.S. government agency and government-sponsored enterprise mortgage-backed securities and collateralized mortgage obligations have been reclassified to conform to current period presentation.

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- Definition Schedule of amortized cost and fair value of the debt securities available for sale portfolio of the entity by contractual maturity. The table includes maturity categories of: due in one year or less; due after one year through five years; due after five years through ten years; and due after ten years. A single line item is provided for "total securities with no stated maturity" in order for the total line item of the table to match total available for sale securities. + References No definition available. + Details
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- Definition Schedule reflecting the gross unrealized losses and fair values of the entity's investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of the date presented. + References No definition available. + Details
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- Definition Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities. + References No definition available. + Details
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- Definition Tabular disclosure of financial instruments held by the entity for its own account for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions. Description may include equity, fixed income, debt or other securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
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