Benefit Plans (Schedule of Net Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Total recognized in AOCI, before income taxes	$ (6,308)	$ 44,255	$ (52,375)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	830	728	2,339
Interest cost	14,069	14,337	12,814
Expected return on assets	(15,607)	(16,035)	(14,938)
Amortization of prior service cost/(credit)	2,279	2,599	467
Amortization of actuarial (gains)/losses	4,227	2,930	4,693
Curtailment gain	0	0	(524)
Net periodic cost (benefit)	5,798	4,559	4,851
Current year actuarial losses/(gains)	7,987	49,488	(47,257)
Cumulative net loss	(4,227)	(2,930)	(4,169)
Amortization of prior service cost/(credit)	(2,279)	(2,599)	(467)
Total recognized in AOCI, before income taxes	1,481	43,959	(51,893)
Total recognized in net periodic cost and AOCI	7,279	48,518	(47,042)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	165	65	99
Interest cost	575	655	563
Expected return on assets	0	0	0
Amortization of prior service cost/(credit)	(639)	(468)	(468)
Amortization of actuarial (gains)/losses	325	236	268
Curtailment gain	0	0	0
Net periodic cost (benefit)	426	488	462
Current year actuarial losses/(gains)	(8,103)	64	(682)
Cumulative net loss	(325)	(236)	(268)
Amortization of prior service cost/(credit)	639	468	468
Total recognized in AOCI, before income taxes	(7,789)	296	(482)
Total recognized in net periodic cost and AOCI	$ (7,363)	$ 784	$ (20)