Investments in Marketable Securities (Tables)

3 Months Ended

Sep. 30, 2013

Investments in Marketable Securities [Abstract]

Summary of Investments in Marketable Securities

				September 30, 2013
				Amortized		Unrealized		Unrealized		Fair
(Dollars in millions)				cost		gains		losses		value
Available-for-sale securities:
	Debt instruments:
		U.S. government and agency obligations		$	104	$	2	$	(1)	$	105
		Municipal debt securities			14		-		-		14
		Certificates of deposit			1,411		1		-		1,412
		Commercial paper			202		-		-		202
		Foreign government debt securities			3		-		-		3
		Corporate debt securities			136		4		(3)		137
		Mortgage-backed securities:
			U.S. government agency		73		2		(1)		74
			Non-agency residential		4		1		-		5
			Non-agency commercial		50		1		(2)		49
		Asset-backed securities			19		-		-		19
	Equity instruments:
		Fixed income mutual funds:
			Short-term sector fund		40		3		-		43
			U.S. government sector fund		320		1		-		321
			Municipal sector fund		20		1		-		21
			Investment grade corporate sector fund		262		43		-		305
			High-yield sector fund		36		7		(1)		42
			Real return sector fund		273		-		-		273
			Mortgage sector fund		558		1		-		559
			Asset-backed securities sector fund		39		9		-		48
			Emerging market sector fund		63		1		-		64
			International sector fund		166		3		-		169
		Equity mutual fund			250		249		-		499
Total investments in marketable securities				$	4,043	$	329	$	(8)	$	4,364

Note 3 – Investments in Marketable Securities (Continued)
					March 31, 2013
				Amortized		Unrealized		Unrealized		Fair
(Dollars in millions)				cost		gains		losses		value
Available-for-sale securities:
	Debt instruments:
		U.S. government and agency obligations		$	101	$	3	$	-	$	104
		Municipal debt securities			14		2		-		16
		Certificates of deposit			2,040		1		-		2,041
		Commercial paper			495		-		-		495
		Foreign government debt securities			3		-		-		3
		Corporate debt securities			122		6		-		128
		Mortgage-backed securities:
			U.S. government agency		83		4		-		87
			Non-agency residential		4		1		-		5
			Non-agency commercial		50		1		-		51
		Asset-backed securities			13		-		-		13
	Equity instruments:
		Fixed income mutual funds:
			Short-term sector fund		40		3		-		43
			U.S. government sector fund		296		16		-		312
			Municipal sector fund		19		3		-		22
			Investment grade corporate sector fund		273		54		-		327
			High-yield sector fund		34		8		-		42
			Real return sector fund		284		9		-		293
			Mortgage sector fund		663		-		(15)		648
			Asset-backed securities sector fund		38		9		-		47
			Emerging market sector fund		63		3		-		66
			International sector fund		163		7		-		170
		Equity mutual fund			259		225		-		484
Total investments in marketable securities				$	5,057	$	355	$	(15)	$	5,397

Summary of the aging of fair value and gross unrealized losses for AFS securities

				Less than 12 months as of
				September 30, 2013				March 31, 2013
				Fair		Unrealized		Fair		Unrealized
(Dollars in millions)				value		losses		value		losses
Available-for-sale securities:
	Debt instruments:
		U.S. government and agency
			obligations	$	28	$	(1)	$	-	$	-
		Corporate debt securities			51		(3)		-		-
		Mortgage backed securities:
			U.S. government agency		29		(1)		-		-
			Non-agency commercial		27		(2)		-		-
	Equity instruments:
		Fixed income mutual funds:
			High-yield sector fund		16		(1)		-		-
			Mortgage sector fund		-		-		532		(12)
	Total investments in marketable
		securities		$	151	$	(8)	$	532	$	(12)

Schedule of realized gains and losses on sales from AFS

		Three Months Ended September 30,				Six Months Ended September 30,
(Dollars in millions)		2013		2012		2013		2012
Available-for-sale securities:
	Realized gains on sales	$	11	$	5	$	16	$	9
	Realized (losses) on sales	$	(2)	$	(1)	$	(3)	$	(2)
	Impairment write-downs	$	(23)	$	-	$	(53)	$	0

Summary of Contractual Maturities of Available-for-Sale Securities

		Due in 1 Year or				Due after 1 Year				Due after 5 Years				Due after
			less			through 5 years				through 10 years				10 years					Total
(Dollars in millions)		Amount		Yield		Amount		Yield		Amount		Yield		Amount		Yield		Amount		Yield
Available-for-Sale Securities:
Debt instruments:
	U.S. government and
	agency obligations	$	7	0.20	%	$	71	1.55	%	$	26	1.56	%	$	1	2.80	%	$	105	1.43	%
	Municipal debt securities		2	2.39			-	-			1	5.57			11	5.69			14	5.18
	Certificates of deposit		1,412	0.43			-	-			-	-			-	-			1,412	0.43
	Commercial paper		202	0.27			-	-			-	-			-	-			202	0.27
	Foreign government debt
	securities		3	2.93			-	-			-	-			-	-			3	2.93
	Corporate debt
	securities		8	4.05			40	4.72			62	3.52			27	3.66			137	3.95
	Mortgage-backed securities:
	U.S. government agency		-	-			-	-			4	3.94			70	3.01			74	3.07
	Non-agency residential		-	-			-	-			-	-			5	11.23			5	11.23
	Non-agency commercial		-	-			4	1.70			1	4.24			44	3.41			49	3.31
	Asset-backed securities		-	-			5	0.74			4	1.83			10	2.68			19	1.97
Debt instruments total			1,634	0.43			120	2.61			98	3.01			168	3.61			2,020	0.95
Equity instruments:
	Fixed income mutual funds																		1,845	3.53
	Equity mutual fund																		499	4.10
Equity instruments total			-				-				-				-				2,344	3.65
Total fair value		$	1,634	0.43	%	$	120	2.61	%	$	98	3.01	%	$	168	3.61	%	$	4,364	2.40	%
Total amortized cost		$	1,633			$	117			$	100			$	166			$	4,043