Employee Benefit Plans Employee Benefit Plans Assumed Health Care Cost Trend Rates (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect on total of service and interest cost components, 1% Increase	5
Effect on total of service and interest cost components, 1% Decrease	(5)
Effect on benefit obligation, 1% Increase	125
Effect on benefit obligation, 1% Decrease	(115)
Health Trend Rates For the Subsequent Tenth Year [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	4.50%	4.50%
Minimum [Member] | Health Trend Rates For the Subsequent Nine Years [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	2.75%	3.66%
Maximum [Member] | Health Trend Rates For the Subsequent Nine Years [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	6.12%	6.87%