Benefit Plans (Schedule of Net Benefit Costs Details) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 198	$ 207	$ 396	$ 415
Interest cost	3,649	3,517	7,298	7,035
Expected return on assets	(3,788)	(3,902)	(7,576)	(7,804)
Amortization of unrecognized prior service costs	75	570	150	1,140
Amortization of actuarial losses/(gains)	830	1,057	1,660	2,113
Net periodic pension cost	964	1,449	1,928	2,899
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	26	41	52	83
Interest cost	64	144	127	288
Amortization of unrecognized prior service costs	(636)	(160)	(1,271)	(319)
Amortization of actuarial losses/(gains)	245	81	490	163
Net periodic pension cost	$ (301)	$ 106	$ (602)	$ 215