Employee Benefit Plans (Details 3)	12 Months Ended
	Dec. 31, 2012
Mid-Cap Stocks | Lower Range
Target Asset Allocations
Target asset allocations	30.00%
Mid-Cap Stocks | Upper Range
Target Asset Allocations
Target asset allocations	70.00%
Fixed Income Investments | Lower Range
Target Asset Allocations
Target asset allocations	30.00%
Fixed Income Investments | Upper Range
Target Asset Allocations
Target asset allocations	70.00%
Cash | Lower Range
Target Asset Allocations
Target asset allocations	0.00%
Cash | Upper Range
Target Asset Allocations
Target asset allocations	15.00%