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Repurchase Agreements (Tables) | 12 Months Ended
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Dec. 31, 2017
Repurchase Agreements [Abstract] |
Schedule of Repurchase Agreements [Table Text Block] | The remaining contractual maturity of the securities sold under agreements to repurchase by class of collateral pledged included in borrowings on the Consolidated Balance Sheets as of December 31, 2017 and December 31, 2016 is presented in the following tables.
| December 31, 2017
| Remaining Contractual Maturity of the Agreements
(Dollars in thousands) | Overnight and continuous |  | Up to 30 Days |  | 30-90 Days |  | Greater than 90 Days |  | Total
Repurchase agreements |  |  |  |  |  |  |  |  |
U.S. Treasury | $ | 556,171 |  |  | $ | — |  |  | $ | 30,000 |  |  | $ | — |  |  | $ | 586,171 |
Gross amount of recognized liabilities for repurchase agreements |  | $ | 586,171 |
| December 31, 2016
| Remaining Contractual Maturity of the Agreements
| Overnight and continuous |  | Up to 30 Days |  | 30-90 Days |  | Greater than 90 Days |  | Total
Repurchase agreements |  |  |  |  |  |  |  |  |
U.S. Treasury | $ | 590,772 |  |  | $ | — |  |  | $ | — |  |  | $ | 30,000 |  |  | $ | 620,772 |
Gross amount of recognized liabilities for repurchase agreements |  | $ | 620,772 |

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- Definition Repurchase Agreements [Abstract] + References No definition available. + Details
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- Definition The entire disclosure for repurchase agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(m)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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