Other Expenses Other Expenses (Restructuring Charges) (Details) - Other Expense [Member] - Severance - Unit Cost Initiative [Member] $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Balance, beginning of period	$ 35
Restructuring charges	11
Cash payments	(8)
Balance, end of period	38
Total restructuring charges incurred since inception of initiative	$ 46