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The estimated actuarial loss and prior service credit that will be amortized from accumulated other comprehensive loss into net periodic benefit cost over the next fiscal year is approximately $5.3 million and $9.7 million, respectively. 

In connection with collective bargaining agreements, we contribute to several multiemployer welfare plans. These plans provide medical benefits to active and retired employees covered under the respective collective bargaining agreement. Contributions are made in accordance with the formula in the relevant agreement. Postretirement costs related to these plans are not reflected above and were approximately $18 million in 2014 , $20 million in 2013 and $18 million in 2012. 

The changes in the benefit obligation and plan assets and other amounts recognized in other comprehensive income/loss were as follows: 

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 Weighted-average assumptions used in the actuarial computations to determine the postretirement benefit obligations were as follows: 

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