Securities Available for Sale (Tables)

12 Months Ended

Dec. 31, 2014

Investments, Debt and Equity Securities [Abstract]

Securities Portfolio Composition

	December 31, 2014
(Dollars in millions)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. Treasury securities		$1,913		$9		$1		$1,921
Federal agency securities	471		15		2		484
U.S. states and political subdivisions	200		9		—		209
MBS - agency	22,573		558		83		23,048
MBS - private	122		2		1		123
ABS	19		2		—		21
Corporate and other debt securities	38		3		—		41
Other equity securities 1	921		2		—		923
Total securities AFS		$26,257		$600		$87		$26,770
	December 31, 2013
(Dollars in millions)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. Treasury securities		$1,334		$6		$47		$1,293
Federal agency securities	1,028		13		57		984
U.S. states and political subdivisions	232		7		2		237
MBS - agency	18,915		421		425		18,911
MBS - private	155		1		2		154
ABS	78		2		1		79
Corporate and other debt securities	39		3		—		42
Other equity securities 1	841		1		—		842
Total securities AFS		$22,622		$454		$534		$22,542

¹ At December 31, 2014, other equity securities was comprised of the following: $376 million in FHLB of Atlanta stock, $402 million in Federal Reserve Bank of Atlanta stock, $138 million in mutual fund investments, and $7 million of other. At December 31, 2013, other equity securities was comprised of the following: $336 million in FHLB of Atlanta stock, $402 million in Federal Reserve Bank of Atlanta stock, $103 million in mutual fund investments, and $1 million of other.

Investment Income [Table Text Block]

	Year Ended December 31
(Dollars in millions)	2014		2013		2012
Taxable interest		$565		$537		$579
Tax-exempt interest	10		10		15
Dividends	38		32		61
Total interest and dividends		$613		$579		$655

Amortized Cost and Fair Value of Investments in Debt Securities by Estimated Average Life

	Distribution of Maturities
(Dollars in millions)	1 Year or Less			1-5 Years			5-10 Years			After 10 Years			Total
Amortized Cost:
U.S. Treasury securities		$200			$1,217			$496			$—			$1,913
Federal agency securities	64			234			36			137			471
U.S. states and political subdivisions	43			34			101			22			200
MBS - agency	2,550			8,992			7,106			3,925			22,573
MBS - private	—			122			—			—			122
ABS	14			3			2			—			19
Corporate and other debt securities	5			33			—			—			38
Total debt securities		$2,876			$10,635			$7,741			$4,084			$25,336
Fair Value:
U.S. Treasury securities		$203			$1,221			$497			$—			$1,921
Federal agency securities	64			244			38			138			484
U.S. states and political subdivisions	43			36			106			24			209
MBS - agency	2,704			9,202			7,219			3,923			23,048
MBS - private	—			123			—			—			123
ABS	14			5			2			—			21
Corporate and other debt securities	5			36			—			—			41
Total debt securities		$3,033			$10,867			$7,862			$4,085			$25,847
Weighted average yield 1	2.34		%	2.40		%	2.78		%	2.90		%	2.59		%

¹Average yields are based on amortized cost and presented on a FTE basis.

Securities in a Continuous Unrealized Loss Position

	December 31, 2014
	Less than twelve months				Twelve months or longer				Total
(Dollars in millions)	Fair Value		Unrealized Losses 2		Fair Value		Unrealized Losses 2		Fair Value		Unrealized Losses 2
Temporarily impaired securities:
U.S. Treasury securities		$150		$1		$—		$—		$150		$1
Federal agency securities	20		—		132		2		152		2
MBS - agency	2,347		6		4,911		77		7,258		83
ABS	—		—		14		—		14		—
Total temporarily impaired securities	2,517		7		5,057		79		7,574		86
OTTI securities 1:
MBS - private	69		1		—		—		69		1
Total OTTI securities	69		1		—		—		69		1
Total impaired securities		$2,586		$8		$5,057		$79		$7,643		$87

	December 31, 2013
	Less than twelve months				Twelve months or longer				Total
(Dollars in millions)	Fair Value		Unrealized Losses 2		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Temporarily impaired securities:
U.S. Treasury securities		$1,036		$47		$—		$—		$1,036		$47
Federal agency securities	398		29		264		28		662		57
U.S. states and political subdivisions	12		—		20		2		32		2
MBS - agency	9,173		358		618		67		9,791		425
ABS	—		—		13		1		13		1
Total temporarily impaired securities	10,619		434		915		98		11,534		532
OTTI securities 1:
MBS - private	105		2		—		—		105		2
Total OTTI securities	105		2		—		—		105		2
Total impaired securities		$10,724		$436		$915		$98		$11,639		$534

¹ Includes OTTI securities for which credit losses have been recorded in earnings in current or prior periods.

² Unrealized losses less than $0.5 million are shown as zero.

Gross Realized Gains and Losses on Sales and OTTI on Securities AFS

	Year Ended December 31
(Dollars in millions)	2014			2013			2012
Gross realized gains		$28			$39			$1,981
Gross realized losses	(42		)	(36		)	—
OTTI losses recognized in earnings	(1		)	(1		)	(7		)
Net securities (losses)/gains		($15	)		$2			$1,974

Measurement Of Investment Credit Losses Assumptions [Table Text Block]

	2014 1	2013	2012
Default rate	2%	2 - 9%	2 - 9%
Prepayment rate	16%	7 - 21%	7 - 21%
Loss severity	46%	46 - 74%	40 - 56%

¹ During the year ended December 31, 2014, all OTTI recognized in earnings related to one private MBS security with a fair value of approximately $16 million at December 31, 2014.