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Securities - Amortized Cost and Fair Value (Details) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2017 USD ($) | Mar. 31, 2016 USD ($) | Dec. 31, 2016 USD ($)
Securities Available-for-Sale |  |  |
Amortized Cost | $ 620,435 |  | $ 545,433
Gross Unrealized Gains | 1,256 |  | 1,011
Gross Unrealized Losses | (10,637) |  | (14,606)
Fair Value | 611,054 |  | 531,838
Other disclosures |  |  |
Purchases | 154,653 | $ 88,005 |
Sales | 64,388 | $ 35,574 |
U.S. government agencies |  |  |
Securities Available-for-Sale |  |  |
Amortized Cost |  |  | 42,511
Gross Unrealized Losses |  |  | (977)
Fair Value |  |  | 41,534
States and political subdivisions |  |  |
Securities Available-for-Sale |  |  |
Amortized Cost | 219,223 |  | 68,718
Gross Unrealized Gains | 856 |  | 258
Gross Unrealized Losses | (572) |  | (273)
Fair Value | 219,507 |  | 68,703
Corporate bonds |  |  |
Securities Available-for-Sale |  |  |
Amortized Cost | 12,807 |  | 10,957
Gross Unrealized Gains | 47 |  | 9
Gross Unrealized Losses | (314) |  | (336)
Fair Value | 12,540 |  | 10,630
Collateralized mortgage obligations |  |  |
Securities Available-for-Sale |  |  |
Amortized Cost | 110,805 |  | 174,352
Gross Unrealized Gains | 119 |  | 374
Gross Unrealized Losses | (2,600) |  | (3,799)
Fair Value | 108,324 |  | 170,927
Asset-backed securities |  |  |
Securities Available-for-Sale |  |  |
Amortized Cost | 146,103 |  | 146,391
Gross Unrealized Gains | 196 |  | 341
Gross Unrealized Losses | (6,413) |  | (8,325)
Fair Value | 139,886 |  | 138,407
FFEL |  |  |
Other disclosures |  |  |
Asset-backed securities | $ 119,000 |  |
Percentage of outstanding principal amount of loans guaranteed by US Department of Education | 97.00 |  |
Total added credit enhancement in the form of overcollaterization and/or subordination of outstanding principal | $ 13,000 |  |
Percentage of total added credit enhancement in the form of overcollaterization and/or subordination of outstanding principal | 10.01 |  |
Collateralized loan obligations |  |  |
Securities Available-for-Sale |  |  |
Amortized Cost | $ 92,564 |  | 102,504
Gross Unrealized Gains | 21 |  | 29
Gross Unrealized Losses | (346) |  | (896)
Fair Value | 92,239 |  | $ 101,637
U.S. government agency mortgage-backed |  |  |
Securities Available-for-Sale |  |  |
Amortized Cost | 38,933 |  |
Gross Unrealized Gains | 17 |  |
Gross Unrealized Losses | (392) |  |
Fair Value | $ 38,558 |  |

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- Definition Investments in notes or bonds that are collateralized by a specific group of underlying assets owned by the issuer of the notes or bonds which are short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 + Details
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