Retirement Benefits (Details 5) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Amounts expected to be recognized in 2014 net periodic benefit cost (Table Amounts)
Net actuarial loss	$ 721
Prior service credit	(79)
Pension Benefits
Amounts expected to be recognized in 2014 net periodic benefit cost (Table Amounts)
Net actuarial loss	712
Prior service credit	(58)
Medical and Life Benefits
Amounts expected to be recognized in 2014 net periodic benefit cost (Table Amounts)
Net actuarial loss	9
Prior service credit	$ (21)