Defined Benefit Pension and Other Post Retirement Plans (Details 5)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Summary of pension Plan weighted-average target allocation and actual asset allocations
Target allocation cash	100.00%
Actual asset allocation cash	100.00%	100.00%
Domestic equity investments [Member]
Summary of pension Plan weighted-average target allocation and actual asset allocations
Target allocation cash	40.00%
Actual asset allocation cash	38.60%	39.60%
Fixed income investments [Member]
Summary of pension Plan weighted-average target allocation and actual asset allocations
Target allocation cash	30.00%
Actual asset allocation cash	28.40%	29.70%
International equity investments [Member]
Summary of pension Plan weighted-average target allocation and actual asset allocations
Target allocation cash	20.00%
Actual asset allocation cash	22.60%	19.50%
Opportunistic investments [Member]
Summary of pension Plan weighted-average target allocation and actual asset allocations
Target allocation cash	10.00%
Actual asset allocation cash	10.00%	11.20%
Cash [Member]
Summary of pension Plan weighted-average target allocation and actual asset allocations
Target allocation cash
Actual asset allocation cash	0.40%