| **Condensed Financial Information (parent company only) (Tables)**               | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
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| **Condensed Financial Information of Parent Company Only Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Schedule Of Parent Company Information Balance Sheet                             | Condensed Balance Sheets December 31, 2014 December 31, 2013Assets   Cash$36,044 $13,228Investment in subsidiaries820,123 745,818Goodwill448 448Other assets6,281 8,695Total assets$862,896 $768,189Liabilities   Borrowings$126,702 $126,702Other liabilities9,367 6,564Total liabilities136,069 133,266Stockholders' equity726,827 634,923Total liabilities and stockholders' equity$862,896 $768,189                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| Schedule Of Parent Company Information Income Statement                          | Condensed Statements of Income and Comprehensive IncomeDecember 31, 2014December 31, 2013December 31, 2012IncomeDividends from subsidiaries$53,231$63,732$30,096Other income5384585Total income53,76963,77730,181ExpensesInterest expense6,6163,5314,655Salaries and employee benefits3,1283,2843,194Net occupancy and equipment expenses442258312Telephone expenses274230Postage and courier expenses1Other expenses1,9722,6171,502Total expenses12,1859,7329,694Income before income tax benefit and equity in undistributed income of subsidiaries41,58454,04520,487Income tax benefit3,9993,1533,316Income before equity in undistributed income of subsidiaries45,58357,19823,803Equity in undistributed (distributions in excess of) income of subsidiaries14,579(12,668)21,319Net income 60,16244,53045,122Preferred stock dividends and discount accretion(2,380)(4,539)Net income available to common stockholders$60,162$42,150$40,583      Net income$60,162$44,530$45,122Other comprehensive income (loss)4,780(911)(1,897)Comprehensive income$64,942$43,619$43,225                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Schedule Of Parent Company Information Cash Flow                                 | Condensed Statement of Cash Flows Year Ended December 31, 201420132012Cash Flow From Operating Activities:   Net income$60,162$44,530$45,122Adjustments to Reconcile Net Income to Net Cash:   Share-based compensation887778632Distributions in excess of (equity in undistributed) income of subsidiaries(14,579)12,668(21,319)Net Change in:   Other assets2,425(1,354)1,902Other liabilities1,466(8,438)1,122Investment in subsidiaries - operating activities(4,517)12,991(1,755)Net cash provided by operating activities$45,844 $61,175 $25,704Cash Flow From Investing Activities:Investment in subsidiaries   $(126)Net cash paid in acquisition$(12,832)Other $240  Net cash provided (used) in investing activities$(12,832) $240 $(126)Cash Flow From Financing Activities:   Cash dividends$(10,694)$(7,992)$(7,442)Repayment of borrowings(55,000)(4,124)Proceeds from issuance of long-term debt 70,000  Preferred stock redemption under small business lending fund (90,783)  Stock issued under employee benefit plans478479449Stock issued under dividend reinvestment and stock purchase plan523325202Stock options exercised56411578Stock redeemed(1,067)(491)(235)Net cash used by financing activities$(10,196) $(83,347) $(11,072)Net change in cash22,816 (21,932) 14,506Cash, beginning of the year13,22835,16020,654Cash, end of year$36,044 $13,228 $35,160 |

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