Employee Benefits Allocation of Plan Assets (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Allocation of Plan Assets
Defined Benefit Plan, Target Plan Asset Allocations	100.00%
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%	100.00%
Equity securities
Allocation of Plan Assets
Defined Benefit Plan, Target Plan Asset Allocations	23.00%
Defined Benefit Plan, Actual Plan Asset Allocations	22.00%	20.00%
Fixed income securities
Allocation of Plan Assets
Defined Benefit Plan, Target Plan Asset Allocations	48.00%
Defined Benefit Plan, Actual Plan Asset Allocations	44.00%	47.00%
Real estate
Allocation of Plan Assets
Defined Benefit Plan, Target Plan Asset Allocations	5.00%
Defined Benefit Plan, Actual Plan Asset Allocations	5.00%	1.00%
Other plan assets
Allocation of Plan Assets
Defined Benefit Plan, Target Plan Asset Allocations	24.00%
Defined Benefit Plan, Actual Plan Asset Allocations	29.00%	32.00%