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Employee Benefit Plans (Fair Value and Allocation Of Plan Assets) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Bancorporation Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 151,067 | $ 168,591 | $ 152,084
Actual % of Plan Assets | 100.00% | 100.00% |
Bancorporation Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 115,974 | $ 126,709 |
Bancorporation Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 35,093 | 41,882 |
Bancorporation Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Cash and equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 2,793 | $ 3,941 |
Actual % of Plan Assets | 1.85% | 2.34% |
Bancorporation Plan | Cash and equivalents | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% | 0.00% |
Bancorporation Plan | Cash and equivalents | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 5.00% | 5.00% |
Bancorporation Plan | Cash and equivalents | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 2,793 | $ 3,941 |
Bancorporation Plan | Cash and equivalents | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Cash and equivalents | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 26,639 | $ 26,892 |
Actual % of Plan Assets | 66.00% | 70.00% |
Bancorporation Plan | Equity securities | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% | 30.00% |
Bancorporation Plan | Equity securities | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 70.00% | 70.00% |
Bancorporation Plan | Equity securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 26,639 | $ 26,892 |
Bancorporation Plan | Equity securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Equity securities | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 0 | $ 0 |
Bancorporation Plan | Debt Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Actual % of Plan Assets | 27.00% | 25.00% |
Bancorporation Plan | Debt Securities | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 15.00% | 15.00% |
Bancorporation Plan | Debt Securities | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 45.00% | 45.00% |
Bancorporation Plan | Equity mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 74,305 | $ 90,466 |
Bancorporation Plan | Equity mutual funds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 73,850 | 84,954 |
Bancorporation Plan | Equity mutual funds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 455 | 5,512 |
Bancorporation Plan | Equity mutual funds | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | US government and government agency securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 13,749 | 15,798 |
Bancorporation Plan | US government and government agency securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | US government and government agency securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 13,749 | 15,798 |
Bancorporation Plan | US government and government agency securities | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Corporate Bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 20,889 | 20,572 |
Bancorporation Plan | Corporate Bonds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Corporate Bonds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 20,889 | 20,572 |
Bancorporation Plan | Corporate Bonds | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Fixed Income Mutual Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 5,748 | 5,163 |
Bancorporation Plan | Fixed Income Mutual Funds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 5,748 | 5,163 |
Bancorporation Plan | Fixed Income Mutual Funds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Fixed Income Mutual Funds | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Alternative investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 6,944 | $ 5,759 |
Actual % of Plan Assets | 5.00% | 3.00% |
Bancorporation Plan | Alternative investments | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% | 0.00% |
Bancorporation Plan | Alternative investments | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% | 30.00% |
Bancorporation Plan | Alternative investments | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 6,944 | $ 5,759 |
Bancorporation Plan | Alternative investments | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Bancorporation Plan | Alternative investments | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 691,467 | $ 712,999 | $ 600,616
Actual % of Plan Assets | 100.00% | 100.00% |
Employer contributions | $ 50,000 | $ 50,000 |
BancShares Plan | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 504,684 | 547,193 |
BancShares Plan | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 186,783 | 165,806 |
BancShares Plan | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Cash and equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 16,236 | $ 67,084 |
Actual % of Plan Assets | 2.00% | 9.00% |
BancShares Plan | Cash and equivalents | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% | 0.00% |
BancShares Plan | Cash and equivalents | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 5.00% | 5.00% |
BancShares Plan | Cash and equivalents | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 16,236 | $ 67,084 |
BancShares Plan | Cash and equivalents | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Cash and equivalents | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 117,300 | $ 76,920 |
Actual % of Plan Assets | 64.00% | 65.00% |
BancShares Plan | Equity securities | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% | 30.00% |
BancShares Plan | Equity securities | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 70.00% | 70.00% |
BancShares Plan | Equity securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 117,300 | $ 76,920 |
BancShares Plan | Equity securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Equity securities | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 0 | $ 0 |
BancShares Plan | Debt Securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Actual % of Plan Assets | 30.00% | 23.00% |
BancShares Plan | Debt Securities | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 15.00% | 15.00% |
BancShares Plan | Debt Securities | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 45.00% | 45.00% |
BancShares Plan | Equity mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 321,023 | $ 381,747 |
BancShares Plan | Equity mutual funds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 319,254 | 360,175 |
BancShares Plan | Equity mutual funds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 1,769 | 21,572 |
BancShares Plan | Equity mutual funds | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | US government and government agency securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 65,545 | 60,663 |
BancShares Plan | US government and government agency securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | US government and government agency securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 65,545 | 60,663 |
BancShares Plan | US government and government agency securities | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Corporate Bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 119,469 | 83,571 |
BancShares Plan | Corporate Bonds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Corporate Bonds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 119,469 | 83,571 |
BancShares Plan | Corporate Bonds | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Fixed Income Mutual Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 23,813 | 20,497 |
BancShares Plan | Fixed Income Mutual Funds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 23,813 | 20,497 |
BancShares Plan | Fixed Income Mutual Funds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Fixed Income Mutual Funds | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Alternative investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 28,081 | $ 22,517 |
Actual % of Plan Assets | 4.00% | 3.00% |
BancShares Plan | Alternative investments | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 0.00% | 0.00% |
BancShares Plan | Alternative investments | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target Allocation | 30.00% | 30.00% |
BancShares Plan | Alternative investments | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 28,081 | $ 22,517 |
BancShares Plan | Alternative investments | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
BancShares Plan | Alternative investments | Fair Value, Inputs, Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 0 | $ 0 |

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