Commitments and Contingencies (Details 3)	12 Months Ended
	Dec. 31, 2014
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	5 years
Total employees | Employees covered by collective bargaining agreements
Collective Bargaining Agreements
Percentage of employees covered by collective bargaining agreements	11.00%
Number of collective bargaining agreements that expire at various times over the next five years	43
Employees covered by collective bargaining agreements that expire during 2015 | Employees covered by collective bargaining agreements
Collective Bargaining Agreements
Percentage of employees covered by collective bargaining agreements	5.30%
Number of collective bargaining agreements that expire within one year	17