Restructuring Costs Restructuring Costs (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Restructuring Reserve [Roll Forward]
Restructuring Reserve Beg	$ 15
Restructuring Additions	1
Restructuring Settlements	(3)
Restructuring Revisions	(1)
Restructuring Reserve End	12
Restructuring and Related Cost, Cost Incurred to Date	55
Restructuring and Related Cost, Expected Cost	55
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve Beg	1
Restructuring Additions	0
Restructuring Settlements	(1)
Restructuring Revisions	0
Restructuring Reserve End	0
Restructuring and Related Cost, Cost Incurred to Date	24
Restructuring and Related Cost, Expected Cost	24
Contract Termination [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve Beg	14
Restructuring Additions	0
Restructuring Settlements	(1)
Restructuring Revisions	(1)
Restructuring Reserve End	12
Restructuring and Related Cost, Cost Incurred to Date	19
Restructuring and Related Cost, Expected Cost	19
Employee Relocation [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve Beg	0
Restructuring Additions	1
Restructuring Settlements	(1)
Restructuring Revisions	0
Restructuring Reserve End	0
Restructuring and Related Cost, Cost Incurred to Date	11
Restructuring and Related Cost, Expected Cost	11
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve Beg	0
Restructuring Additions	0
Restructuring Reserve, Settled without Cash	0
Restructuring Revisions	0
Restructuring Reserve End	0
Restructuring and Related Cost, Cost Incurred to Date	1
Restructuring and Related Cost, Expected Cost	$ 1