Comprehensive Income (Loss) (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, Recognition of net actuarial loss for pension settlement costs, before tax	$ 43
Pension Benefits [Member] | Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Discount rate - used at year end to value obligation	4.10%
Other Comprehensive Income (Loss), before Reclassifications, before Tax	$ 48
Other comprehensive income, Recognition of net actuarial loss for pension settlement costs, before tax	$ 43