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Other Employee Benefits MultiEmployer Plans (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Net periodic (benefit) cost $ 45,463,000 $ (198,713,000) $ 16,687,000
Long term disability [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Net periodic (benefit) cost 2,128 2,619 $ 2,213
Defined Benefit Plan, Benefit Obligation $ 19,144,000 $ 19,789,000  
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate 3.71% 3.18% 3.53%
Retiree Health Benefit Act of 1992 [Domain]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Multiemployer Plan, Period Contributions $ 8,455,000 $ 9,239,000 $ 10,121,000
Multiemployer Plan, Withdrawal Obligation 93,795,000    
Non-Pension Multiemployer Plans [Domain]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Letters of Credit Outstanding, Amount 19,170,000 21,473,000 21,394,000
401k Defined Contribution [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Defined Contribution Plan, Employer Discretionary Contribution Amount 12,260    
Defined Contribution Plan, Cost Recognized $ 20,784,000 $ 20,058,000 $ 18,341,000