Litigation and Related Matters (Narrative) (Details) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2010 site	Jun. 30, 2017 USD ($) Litigation	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Litigation site	Jun. 30, 2016 USD ($)	Dec. 31, 2007	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Number of active and independent litigation matters for which pursuing coverage and recoveries | Litigation		2		2
Potential environmental liabilities | $		$ 5.5		$ 5.5			$ 4.7
Reserves for potential environmental liabilities | $		$ 0.7	$ 0.1	$ 1.3	$ 0.8
Macon Site [Member]
Loss Contingencies [Line Items]
Number of landfills listed as Superfund site | site				2
Number of landfills AWI entered into an Administrative Order on Consent for a Removal Action | site	1
Submission date of final report to EPA	Oct. 11, 2016
Elizabeth City [Member]
Loss Contingencies [Line Items]
Percentage of site costs Navy agreed to pay						33.33%