Other Employee Benefits MultiEmployer Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Letters of Credit Outstanding, Amount	$ 60,230,000	$ 66,054,000
Voluntary Severance Incentive Program			13,304,000
Non-Pension Multiemployer Plans [Domain]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Letters of Credit Outstanding, Amount	21,394,000	60,741,000	63,614,000
Retiree Health Benefit Act of 1992 [Domain]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Multiemployer Plan, Period Contributions	10,121,000	11,435,000	12,358,000
Multiemployer Plan, Withdrawal Obligation	110,864,000
401k Defined Contribution [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Cost Recognized	$ 21,606,000	$ 23,748,000	$ 24,127,000