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Securities (Narrative) (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 USD ($) issuance security | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items] |  |  |
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds | $ | $ 124.1 | $ 95.4 | $ 63.3
Number Of Issuances Of Securities Exceeding Shareholders Equity Threshold | issuance | 0 |  |
U.S. Government and Government-Sponsored Enterprise Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Number Of Securities In Unrealized Loss Position | 22 |  |
Number Of Securities In Continuous Loss Position For Twelve Months or More | 0 |  |
US Treasury Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Number Of Securities In Unrealized Loss Position | 1 |  |
Other Securities [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Issuances Of Securities Exceeding Shareholders Equity Threshold, Percent | 10.00% |  |
Number Of Securities In Unrealized Loss Position | 2 |  |
Number Of Securities In Continuous Loss Position For Twelve Months or More | 1 |  |
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Number Of Securities In Unrealized Loss Position | 192 |  |
Number Of Securities In Continuous Loss Position For Twelve Months or More | 50 |  |
Municipal Bonds [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Number Of Securities In Unrealized Loss Position | 180 |  |
Number Of Securities In Continuous Loss Position For Twelve Months or More | 5 |  |

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