Employee Benefit Plans - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 years		Dec. 31, 2013		Dec. 31, 2012 units		Apr. 22, 2014	Dec. 31, 2015
Document Period End Date	Dec. 31, 2014
Vesting period of stock options	3
Long Term Incentive Deferred Cash Expense	$ 203		$ 150		$ 155
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 8 months 5 days
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			6.00%
Defined Benefit Plan Effect of 25 Basis Point Increase or Decrease in Expected Return on Plan Assets	7
Defined Benefit Plan Effect of 25 Basis Point increase or Decrease in Discount Rate	1
Pension Account Effective Interest Crediting Rate	3.89%
Defined Benefit Plan, Plan Amendments			76
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	6.00%
Defined Contribution Plan, Cost Recognized	98				96
Defined Contribution Plan, Employer Discretionary Contribution Amount	19		19		38
Share Based Compensation Arrangement By Share Based Payment Award Options Available For Additional Grant	18						17
Fair value of options granted per share			$ 7.37		$ 7.83
Contributed To Postretirement Welfare Plan	1
Number of restricted stock units granted					574,257
Fair Value Of Restricted Stock Units Per Unit					21.67
Balance of restricted stock unit	21		17
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%
Discretionary One-time Contribution, Employer Matching Percent [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	1.00%		1.00%		2.00%
Pension Plans, Defined Benefit
Defined Benefit Plan Basis Used To Determine Overall Expected Long Term Rate Of Returns On Assets Assumption Historical			0.00%
Defined Benefit Plan, Plan Amendments	0	[1]	0	[1]
Defined Benefit Plan, Contributions by Employer	6	[1]	8	[1]
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	21
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	7.20%	[2]	7.20%	[2]	7.20%	[2]
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan, Plan Amendments	0	[3]	76	[3]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Expected Long Term Return on Assets	5.00%
Defined Benefit Plan, Contributions by Employer	0	[3]	0	[3]
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year	$ (6)
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	3.41%	[4]	3.25%	[4]	4.06%	[4]
Other PostRetirement Benefit Plan, Defined Benefit, Pre-tax [Member]
Defined Benefit Plan Basis Used To Determine Overall Expected Long Term Rate Of Returns On Assets Assumption Historical	5.25%		5.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	5.00%
Other Postretirement Benefit Plan, Defined Benefit, After-tax [Member] [Member]
Defined Benefit Plan Basis Used To Determine Overall Expected Long Term Rate Of Returns On Assets Assumption Historical	3.41%		3.25%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	3.25%
Suntrust Retirement Plan [Member] | Pension Plans, Defined Benefit
Defined Benefit Plan Basis Used To Determine Overall Expected Long Term Rate Of Returns On Assets Assumption Historical	7.20%		7.00%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Expected Long Term Return on Assets								6.95%
NCF Retirement Plan [Member] | Pension Plans, Defined Benefit
Defined Benefit Plan Basis Used To Determine Overall Expected Long Term Rate Of Returns On Assets Assumption Historical	6.65%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Expected Long Term Return on Assets								6.15%
Participants Younger Than 65 [Member]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	7.50%

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

[2] 1 Administrative fees are recognized in service cost for each of the periods presented.

[3] 2 Plan remeasured at December 31, 2013 due to plan amendment.

[4] 3 The weighted average shown is determined on an after-tax basis.