Change in Plan Assets (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Pension Plans, Defined Benefit
Beginning balance	$ 2,550		$ 2,522
Actual return on plan assets	350		129
Employer contributions	26		8
Plan participants' contributions	0		0
Benefits paid	(184)		(109)
Ending balance	2,742		2,550
Other Postretirement Benefit Plans, Defined Benefit
Beginning balance	161	[1]	165
Actual return on plan assets	17		7
Employer contributions	0		0
Plan participants' contributions	22		22
Benefits paid	(36)		(33)
Ending balance	$ 164	[2]	$ 161	[1]

[1] Schedule does not include accrued income.

[2] Schedule does not include accrued income. Fair ValueMeasurements as ofDecember 31, 2011 1(Dollars in millions)Assets Measuredat Fair Value asof December 31,2011 Quoted Prices InActive Marketsfor IdenticalAssets (Level 1) SignificantOtherObservableInputs(Level 2) SignificantUnobservableInputs(Level 3)Mutual funds: Large cap fund $37 $37 $— $—Investment grade tax-exempt bond 25 25 — —International fund 6 6 — —Common and collective funds: SunTrust Reserve Fund 1 — 1 —SunTrust Equity Fund 37 — 37 —SunTrust Georgia Tax-Free Fund 26 — 26 —SunTrust National Tax-Free Fund 17 — 17 —SunTrust Aggregate Fixed Income Fund 7 — 7 —SunTrust Short-Term Bond Fund 5 — 5 —Total plan assets $161 $68 $93 $—