Commitments and Contingencies (Details 3)	12 Months Ended
	Dec. 31, 2012 item
Environmental Contingencies
Ownership interest in domestic subsidiaries (as a percent)	100.00%
Employees covered by collective bargaining agreements
Collective Bargaining Agreements
Expiration period of collective bargaining agreements (in years)	5
Total employees | Employees covered by collective bargaining agreements
Collective Bargaining Agreements
Percentage of employees covered by collective bargaining agreements	11.00%
Employees covered by collective bargaining agreements that expire during 2012 | Employees covered by collective bargaining agreements
Collective Bargaining Agreements
Percentage of employees covered by collective bargaining agreements	3.00%
Number of collective bargaining agreements that expire within one year	16