Restructuring Charges (Schedule of restructuring charges) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Restructuring Reserve [Roll Forward]
Beginning reserve balance			$ 16
Charged to Costs and Expenses	$ 4	$ 0	8	$ 1
Payments and Other			(11)
Ending reserve balance	13		13
Branch closure charges
Restructuring Reserve [Roll Forward]
Beginning reserve balance			13
Charged to Costs and Expenses			4
Payments and Other			(5)
Ending reserve balance	12		12
Severance costs
Restructuring Reserve [Roll Forward]
Beginning reserve balance			3
Charged to Costs and Expenses			4
Payments and Other			(6)
Ending reserve balance	1		1
Closed Restructuring Programs
Restructuring Reserve [Roll Forward]
Beginning reserve balance			13
Charged to Costs and Expenses			1
Payments and Other			(5)
Ending reserve balance	9		9
Closed Restructuring Programs | Branch closure charges
Restructuring Reserve [Roll Forward]
Beginning reserve balance			13
Charged to Costs and Expenses			1
Payments and Other			(5)
Ending reserve balance	9		9
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			7
Payments and Other			(6)
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			0
Ending reserve balance	3		3
2015-2016 Cost Savings Restructuring Program | Severance costs
Restructuring Reserve [Roll Forward]
Beginning reserve balance			3
Charged to Costs and Expenses			4
Payments and Other			(6)
Ending reserve balance	$ 1		$ 1