Restructuring Charges (Schedule of restructuring charges) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Restructuring Reserve [Roll Forward]
Beginning reserve balance			$ 16
Charged to Costs and Expenses	$ 2	$ 0	4	$ 1
Payments and Other			(6)
Ending reserve balance	14		14
Branch closure charges
Restructuring Reserve [Roll Forward]
Beginning reserve balance			13
Charged to Costs and Expenses			2
Payments and Other			(3)
Ending reserve balance	12		12
Severance costs
Restructuring Reserve [Roll Forward]
Beginning reserve balance			3
Charged to Costs and Expenses			2
Payments and Other			(3)
Ending reserve balance	2		2
Closed Restructuring Programs
Restructuring Reserve [Roll Forward]
Beginning reserve balance			13
Charged to Costs and Expenses			(1)
Payments and Other			(2)
Ending reserve balance	10		10
Closed Restructuring Programs | Branch closure charges
Restructuring Reserve [Roll Forward]
Beginning reserve balance			13
Charged to Costs and Expenses			(1)
Payments and Other			(2)
Ending reserve balance	10		10
Closed Restructuring Programs | Severance costs
Restructuring Reserve [Roll Forward]
Beginning reserve balance			0
Charged to Costs and Expenses			0
Payments and Other			0
Ending reserve balance	0		0
2015-2016 Cost Savings Restructuring Program
Restructuring Reserve [Roll Forward]
Beginning reserve balance			3
Charged to Costs and Expenses			5
Payments and Other			(4)
Ending reserve balance	4		4
2015-2016 Cost Savings Restructuring Program | Branch closure charges
Restructuring Reserve [Roll Forward]
Beginning reserve balance			0
Charged to Costs and Expenses			3
Payments and Other			(1)
Ending reserve balance	2		2
2015-2016 Cost Savings Restructuring Program | Severance costs
Restructuring Reserve [Roll Forward]
Beginning reserve balance			3
Charged to Costs and Expenses			2
Payments and Other			(3)
Ending reserve balance	$ 2		$ 2