| **Supplemental Comprehensive Income Disclosures**            | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
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| **Supplemental Comprehensive Income Disclosures [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Supplemental Comprehensive Income Disclosures                | Supplemental Comprehensive Income DisclosuresThe following table identifies the related tax effects allocated to each component of other comprehensive income (“OCI”) in the Condensed Consolidated Statements of Comprehensive Income.  Reclassification adjustments related to securities available for sale are included in the "Net securities gains" line and reclassification adjustments related to losses on derivatives are included in the "Other operating expenses" line in the Condensed Consolidated Statements of Income.  For the Nine Months Ended September 30, 2016 2015 Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount (dollars in thousands)Unrealized gains on securities:           Unrealized holding gains on securities arising during the period$13,121 $(4,593) $8,528 $12,510 $(4,377) $8,133Reclassification adjustment for gains on securities included in net income(28) 10 (18) (125) 44 (81)Total unrealized gains on securities13,093 (4,583) 8,510 12,385 (4,333) 8,052Unrealized gains on derivatives:           Unrealized holding gains on derivatives arising during the period1,038 (363) 675 2,172 (760) 1,412Reclassification adjustment for gains on derivatives included in net income(57) 20 (37) (6) 2 (4)Total unrealized gains on derivatives981 (343) 638 2,166 (758) 1,408Total other comprehensive income$14,074 $(4,926) $9,148 $14,551 $(5,091) $9,460 For the Three Months Ended September 30, 2016 2015 Pretax Amount Tax (Expense) Benefit Net of Tax Amount Pretax Amount Tax (Expense) Benefit Net of Tax Amount (dollars in thousands)Unrealized (losses) gains on securities:           Unrealized holding (losses) gains on securities arising during the period$(751) $262 $(489) $6,344 $(2,221) $4,123Reclassification adjustment for losses on securities included in net income— — — — — —Total unrealized (losses) gains on securities(751) 262 (489) 6,344 (2,221) 4,123Unrealized (losses) gains on derivatives:           Unrealized holding (losses) gains on derivatives arising during the period(1,056) 370 (686) 1,504 (526) 978Reclassification adjustment for gains on derivatives included in net income(16) 6 (10) — — —Total unrealized (losses) gains on derivatives(1,072) 376 (696) 1,504 (526) 978Total other comprehensive (loss) income$(1,823) $638 $(1,185) $7,848 $(2,747) $5,101 The following table details the change in components of OCI for the nine months endedSeptember 30: 2016 2015 Securities Available for SalePost-Retirement ObligationDerivativesAccumulated Other Comprehensive Income Securities Available for SalePost-Retirement ObligationDerivativesAccumulated Other Comprehensive Income (dollars in thousands)Balance at December 31$(2,956)$10$560$(2,386) $(4,875)$76$300$(4,499)Other comprehensive income before reclassification adjustment8,528—6759,203 8,133—1,4129,545Amounts reclassified from accumulated other comprehensive (loss) income(18)—(37)(55) (81)—(4)(85)Net other comprehensive income during the period8,510—6389,148 8,052—1,4089,460Balance at September 30$5,554$10$1,198$6,762 $3,177$76$1,708$4,961 |

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| - Definition
Supplemental Comprehensive Income Disclosures [Abstract]
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No definition available.
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| - Definition
The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.
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