Labor Union Contracts (Details)	12 Months Ended			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012 Employees covered under collective bargaining agreements Employee	Dec. 31, 2013 Employees covered under collective bargaining agreements	Dec. 31, 2012 Employees covered under expired collective bargaining agreements Employee	Dec. 31, 2013 Employees covered under expired collective bargaining agreements
Labor Union Contracts
Percentage of employees who are members of bargaining units (percent)	36.00%		26.00%		3.00%
Number of employees covered under the agreement (employees)		12,000		1,600
Collective bargaining agreements term	4 years