Pension and Other Post Retirement Benefit Plans Pension and Other Post Retirement Benefit Plans - Schedule of Maturities of Plan's Debt Securities (In Years) (Details) (Debt securities)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Minimum
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities	31 days	45 days
Maximum
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities	9 years 0 months 29 days	10 years 9 months 29 days
Weighted Average
Defined Benefit Plan Disclosure [Line Items]
Maturities of debt securities	4 years 11 months 19 days	5 years 4 months 17 days