Pensions and Other Postretirement Benefit Plans (Schedule of Pension Plans with Projected Benefit Obligation and Accumulated Benefit Obligation in Excess of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Plans with projected benefit obligation in excess of plan assets:
Projected benefit obligation	$ 121,600	$ 120,312
Accumulated benefit obligation	119,753	117,447
Fair value of plan assets	83,622	81,421
Plans with accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	121,511	120,312
Accumulated benefit obligation	119,728	117,447
Fair value of plan assets	$ 83,558	$ 81,421