Retirement Plan (Weighted Average Assumptions Used for Health Care Trend Rates) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Benefit Obligation
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.45%	4.60%
Current health care trend rate	8.10%	8.40%
Ultimate health care trend rate	5.00%	5.00%
Year rate reaches ultimate trend rate	2023	2023
Net Periodic Benefit Expense
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.60%	5.75%	5.50%
Current health care trend rate	8.40%	8.70%	9.00%
Ultimate health care trend rate	5.00%	5.00%	5.00%
Year rate reaches ultimate trend rate		2023	2023