Components of Net Periodic Benefit Cost (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Pension Plans, Defined Benefit
Defined Benefit Plan, Service Cost	$ 5	[1],[2]	$ 5	[1],[2]	$ 5	[1]
Defined Benefit Plan, Actuarial Gain (Loss)	401	[2]	(195)	[2]
Defined Benefit Plan, Interest Cost	124	[1],[2]	113	[1],[2]	119	[1]
Defined Benefit Plan, Expected Return on Plan Assets	(200)	[1]	(192)	[1]	(178)	[1]
Defined Benefit Plan, Amortization of Gains (Losses)	16	[1]	26	[1]	25	[1]
Net periodic benefit cost	(55)	[1]	(48)	[1]	(27)	[1]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.98%	[1]	4.08%	[1]	4.63%	[1],[3]
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	[1]	0	[1]	2	[1]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	7.20%	[1]	7.20%	[1]	7.20%	[1]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	[1]	0	[1]	0	[1]
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan, Service Cost	0	[4]	0	[4]	0
Defined Benefit Plan, Actuarial Gain (Loss)	(10)	[4]	1	[4]
Defined Benefit Plan, Interest Cost	3	[4]	6	[4]	7
Defined Benefit Plan, Expected Return on Plan Assets	(5)		(6)		(7)
Defined Benefit Plan, Amortization of Gains (Losses)	0		0		0
Net periodic benefit cost	(8)		0		0
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.15%		3.45%		4.10%
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0		0		0
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	3.41%	[5]	3.25%	[5]	4.06%	[5]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	$ (6)		$ 0		$ 0

[1] 1 Administrative fees are recognized in service cost for each of the periods presented.

[2] 1 Employer contributions represent the benefits that were paid to nonqualified plan participants. SERPs are not funded through plan assets.

[3] 2 Interim remeasurement was required on September 15, 2012 for the SunTrust SERP to reflect settlement accounting.

[4] 2 Plan remeasured at December 31, 2013 due to plan amendment.

[5] 3 The weighted average shown is determined on an after-tax basis.