Employee Benefit Plans (Supplemental Non-qualified Unfunded Plans) (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Officers and Key Employees | Supplemental Non-qualified Unfunded Plans
Deferred Compensation Arrangement with Individual, Postretirement Benefits
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 300,000	$ 300,000	$ 300,000
Deferred Compensation Arrangement with Individual, Recorded Liability	1,600,000	1,700,000
Other Postretirement Benefit Plans, Defined Benefit
Deferred Compensation Arrangement with Individual, Postretirement Benefits
Expected Future Benefit Payments, Year Two	500,000
Expected Future Benefit Payments, Year Three	500,000
Expected Future Benefit Payments, Year Four	500,000
Expected Future Benefit Payments, Year Five	$ 500,000