Summary of Significant Accounting Policies (Employee Benefit Plans) (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Number of non-contributory qualified pension plans	2
Assumed rate of retun on assets	7.25%
Rate of compensation increase for pay-related plans	3.75%
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Weighted average discount rates	4.89%	5.49%	6.50%
Assumed rate of retun on assets	7.25%	7.25%	8.25%
Rate of compensation increase for pay-related plans	3.75%	3.95%	3.90%
Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Weighted average discount rates	5.45%	5.90%	6.50%
Assumed rate of retun on assets	7.25%	7.25%	8.25%
Rate of compensation increase for pay-related plans	3.61%	3.69%	3.55%