Securities Available for Sale (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 20,464		$ 25,170
Unrealized Gains	1,013		2,989
Unrealized Losses	10		42
Available-for-sale Securities	21,467		28,117
US Treasury Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	213		671
Unrealized Gains	11		23
Unrealized Losses	0		0
Available-for-sale Securities	224		694
US Government Agencies Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,713		1,843
Unrealized Gains	89		89
Unrealized Losses	0		0
Available-for-sale Securities	1,802		1,932
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	343		437
Unrealized Gains	18		21
Unrealized Losses	6		4
Available-for-sale Securities	355		454
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,705		20,480
Unrealized Gains	881		743
Unrealized Losses	0		0
Available-for-sale Securities	17,586		21,223
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	213		252
Unrealized Gains	4		0
Unrealized Losses	0		31
Available-for-sale Securities	217		221
Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost			50
Unrealized Gains			0
Unrealized Losses			0
Available-for-sale Securities			50
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	260		460
Unrealized Gains	5		11
Unrealized Losses	4		7
Available-for-sale Securities	261		464
Corporate And Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	42		49
Unrealized Gains	4		2
Unrealized Losses	0		0
Available-for-sale Securities	46		51
Equity Securities, Coca Cola
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost			0
Unrealized Gains			2,099
Unrealized Losses			0
Available-for-sale Securities			2,099
Equity Securities, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	975	[1]	928	[1]
Unrealized Gains	1	[1]	1	[1]
Unrealized Losses	0	[1]	0	[1]
Available-for-sale Securities	976	[1]	929	[1]
Equity Securities, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Federal Reserve Bank Stock	$ 401		$ 398

[1] At September 30, 2012, other equity securities included the following securities at cost: $432 million in FHLB of Atlanta stock, $401 million in Federal Reserve Bank stock, and $141 million in mutual fund investments. At December 31, 2011, other equity securities included the following securities at cost: $342 million in FHLB of Atlanta stock, $398 million in Federal Reserve Bank stock, and $187 million in mutual fund investments.