Accumulated Other Comprehensive Loss - Reconciliation of Adjustments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncome [Line Items]
Total employee benefit amounts reclassified from accumulated other comprehensive loss, net	$ 8,866		$ (9,970)	$ 62,495
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment
ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncome [Line Items]
Amortization of actuarial loss	8,708	[1]
Amortization of prior service credit	(948)
Plan settlement	671	[1]
Total employee benefit amounts reclassified from accumulated other comprehensive loss	8,431
Tax expense	435
Total employee benefit amounts reclassified from accumulated other comprehensive loss, net	$ 8,866

[1] These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See note (10) "Employee Benefit Plans" for details.