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      <ShortName>EMPLOYEE BENEFITS, Employee Health Benefits (Details)</ShortName>
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      <ShortName>EMPLOYEE BENEFITS, Non-Qualified Plans (Details)</ShortName>
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      <Position>79</Position>
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      <ShortName>STOCK-BASED COMPENSATION, Equity Incentive Plan (Details)</ShortName>
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      <Position>80</Position>
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      <Role>http://city.bank.com/role/StockbasedCompensationStockOptionsActivityDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION, Stock Options Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
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      <ReportType>Sheet</ReportType>
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      <ShortName>STOCK-BASED COMPENSATION, Fair Value Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
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      <Role>http://city.bank.com/role/StockbasedCompensationRestrictedStockAwardsAndUnitsDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION, Restricted Stock Awards and Units (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
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