Asset Allocation for the Other Postretirment Benefit Plan and the Target Allocation, by Asset Catergory (Detail)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan, Percentage of Plan Assets [Abstract]
Percentage of Plan Assets	100.00%		100.00%
Equity Securities
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	50.00%	[1]
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	75.00%	[1]
Equity Securities | Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	20.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	40.00%
Defined Benefit Plan, Percentage of Plan Assets [Abstract]
Percentage of Plan Assets	30.00%		50.00%
Debt Securities [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	25.00%	[1]
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	50.00%	[1]
Debt Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	50.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	70.00%
Defined Benefit Plan, Percentage of Plan Assets [Abstract]
Percentage of Plan Assets	61.00%		50.00%
Cash Equivalents [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	0.00%	[1]
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	5.00%	[1]
Cash Equivalents [Member] | Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	5.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	15.00%
Defined Benefit Plan, Percentage of Plan Assets [Abstract]
Percentage of Plan Assets	9.00%		0.00%

[1] 1SunTrust Pension Plan only.