Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands			3 Months Ended
	Feb. 22, 2015	Oct. 14, 2014	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Actual return for qualified pension plan assets			16.60%	3.50%
Assumptions used calculating net periodic Benefit Cost, expected long-term return on assets			7.50%
Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Recognized net settlement charges			$ (441)	$ 0
Contributions by employer			3,600
Qualified Pension Plans | Pension Plans, Defined Benefit, Represented Employees
Defined Benefit Plan Disclosure [Line Items]
Benefit accrual rate as a percent of prior rate		50.00%
Length of credited service, capped		30 years
Period after ratification for which employees receive monthly reimbursements	30 months
Medical insurance premiums reimbursement, age of beneficiary, maximum	65 years
Post- employment Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Recognized net settlement charges			0	$ 0
Contributions by employer			$ 1,200