Subsequent Events (Details) - Subsequent Event $ in Millions			3 Months Ended
	Oct. 20, 2017 USD ($)	Oct. 18, 2017 USD ($) Employee	Dec. 31, 2017 USD ($)
Subsequent Event [Line Items]
Number of retirees | Employee		3,800
Reduction of qualified pension plan obligations		$ 225
Pension Plan
Subsequent Event [Line Items]
Discretionary contribution to the Pension Plans	$ 100
Scenario, Forecast
Subsequent Event [Line Items]
Pension settlement charge			$ 95