Commitments and Contingencies Asbestos Claimant and Settlement (Details) - Asbestos [Member]	6 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($) claimants	Dec. 31, 2017 USD ($) claimants	Dec. 31, 2016 claimants
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	4,841	5,256	5,339
Loss Contingency, New Claims Filed, Number	91	173
Loss Contingency, Claims Dismissed, Number	484	231
Loss Contingency, Claims Settled, Number	22	25
Average settlement amount per claim during period | $	$ 6,545	$ 8,930
Total defense costs during period | $	$ 1,125,386	$ 2,280,000