Contingencies (Schedule of Changes in Claims) (Details) - Asbestos Litigation [Member] $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) claims	Dec. 31, 2016 USD ($) claims	Dec. 31, 2015 USD ($) claims	Dec. 31, 2014 USD ($) claims	Dec. 31, 2013 USD ($) claims	Dec. 31, 2012 USD ($) claims
Loss Contingencies [Line Items]
Opening Number of Claims	3,745	3,791	3,821	4,299	4,463	4,446
Claims Dismissed, Settled, or Resolved	75	148	116	625	230	90
New Claims	57	102	86	147	66	107
Closing Number of Claims	3,727	3,745	3,791	3,821	4,299	4,463
Amounts Paid (thousands) to Settle or Resolve ($) | $	$ 10	$ 758	$ 164	$ 437	$ 78	$ 530