Retirement Benefits (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2007
Discount rate:
Discount rate on net periodic benefit costs				6.75%
Annual salary increase	3.84%	3.84%	4.18%	3.75%
Pension Plans [Member]
Discount rate:
Discount rate on net periodic benefit costs	4.98%	5.52%	5.93%
Long-term return on plan assets:
Long-term return on plan assets on net periodic benefit costs	8.45%	8.45%	8.20%
Other Postretirement Benefits [Member]
Discount rate:
Discount rate on net periodic benefit costs	4.88%	5.40%	5.83%
Long-term return on plan assets:
Long-term return on plan assets on net periodic benefit costs	7.39%	7.40%	7.51%