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Consolidated Statements of Stockholders' Equity (USD $) In Thousands | Common stock [Member] | Additional paid-in capital [Member] | Retained earnings [Member] | Accumulated other comprehensive income (loss) [Member] | Treasury stock [Member] | Comprehensive income [Member] | Total
--- | --- | --- | --- | --- | --- | --- | ---
Beginning of year at Dec. 31, 2009 | $ 191,646 | $ 231,933 | $ 1,138,978 | $ (12,460) | $ (547,722) |  |
Dividend reinvestment plan (shares: 74,777 - 2011; 81,471 - 2010) | 163 | 1,098 |  |  |  |  |
Stock purchase and compensation plans (shares: 607,059 - 2011; 284,793 - 2010) | 569 | 8,441 |  |  |  |  |
Net income |  |  | 41,766 |  |  | 41,766 | 41,766
Dividends to stockholders ($0.39 per share - 2011 and 2010) |  |  | (21,248) |  |  |  |
Non-credit portion of other-than-temporary impairment losses recognized in other comprehensive income, net of deferred income tax |  |  |  | 3,026 |  |  | 3,026
Other net unrealized gains on investment securities, net of deferred income tax |  |  |  | 55,556 |  |  |
Total unrealized gains on investment securities |  |  |  | 58,582 |  | 58,582 | 58,582
Defined benefit pension plans, net of deferred income tax |  |  |  | 2,098 |  | 2,098 | 2,098
Comprehensive income |  |  |  |  |  | 102,446 | 102,446
Acquisition of treasury stock (shares: 137,667 - 2011; 98,419 - 2010) |  |  |  |  | (1,528) |  |
End of period at Sep. 30, 2010 | 192,378 | 241,472 | 1,159,496 | 48,220 | (549,250) |  | 1,092,316
Beginning of year at Dec. 31, 2010 | 192,725 | 244,613 | 1,176,155 | 7,024 | (549,408) |  | 1,071,109
Dividend reinvestment plan (shares: 74,777 - 2011; 81,471 - 2010) | 150 | 1,066 |  |  |  |  |
Stock purchase and compensation plans (shares: 607,059 - 2011; 284,793 - 2010) | 1,214 | 8,260 |  |  |  |  |
Net income |  |  | 3,732 |  |  | 3,732 | 3,732
Dividends to stockholders ($0.39 per share - 2011 and 2010) |  |  | (21,579) |  |  |  |
Non-credit portion of other-than-temporary impairment losses recognized in other comprehensive income, net of deferred income tax |  |  |  | 336 |  |  | 336
Other net unrealized gains on investment securities, net of deferred income tax |  |  |  | 22,617 |  |  |
Total unrealized gains on investment securities |  |  |  | 22,953 |  | 22,953 | 22,953
Defined benefit pension plans, net of deferred income tax |  |  |  | 2,187 |  | 2,187 | 2,187
Comprehensive income |  |  |  |  |  | 28,872 | 28,872
Acquisition of treasury stock (shares: 137,667 - 2011; 98,419 - 2010) |  |  |  |  | (2,537) |  |
End of period at Sep. 30, 2011 | $ 194,089 | $ 253,939 | $ 1,158,308 | $ 32,164 | $ (551,945) |  | $ 1,086,555

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