Employee Benefit Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) pension_plan	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of Union Pension Plans | pension_plan	2
Defined contribution plan, expenses	$ 8,900	$ 8,300	$ 7,100
Defined benefit plan, assumed rate of increase in health care cost trend rate for 2013	5.10%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.30%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 148,906	137,851
Defined Benefit Plan, Fair Value of Plan Assets	142,742	127,267	100,556
Actuarial loss	574	37,934
Defined Benefit Plan, Future Amortization of Gain (Loss)	(4,900)
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)	(200)
Contributions estimated to be paid	22,900
Plan amendment	(3,610)	0
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0	$ 0
Actuarial loss	(579)	1,951
Defined Benefit Plan, Future Amortization of Gain (Loss)	(700)
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)	(3,300)
Contributions estimated to be paid	600
Plan amendment	$ 0	$ 0
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	67.00%	67.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%	30.00%
Scenario, Plan [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	70.00%
Scenario, Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	30.00%
Salaried and USW [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 146,800
Defined Benefit Plan, Fair Value of Plan Assets		$ 140,600