Investments in Marketable Securities (Tables)

12 Months Ended

Mar. 31, 2014

Investments in Marketable Securities [Abstract]

Summary of Investments in Marketable Securities

				March 31, 2014
				Amortized		Unrealized		Unrealized		Fair
(Dollars in millions)				cost		gains		losses		value
Available-for-sale securities:
	Debt instruments:
		U.S. government and agency obligations		$	652	$	1	$	(1)	$	652
		Municipal debt securities			10		1		-		11
		Certificates of deposit			1,599		-		-		1,599
		Commercial paper			507		-		-		507
		Corporate debt securities			164		6		(1)		169
		Mortgage-backed securities:
			U.S. government agency		60		1		(1)		60
			Non-agency residential		4		1		-		5
			Non-agency commercial		44		1		(2)		43
		Asset-backed securities			27		-		-		27
	Equity instruments:
		Fixed income mutual funds:
			Short-term sector fund		41		3		-		44
			U.S. government sector fund		329		-		(2)		327
			Municipal sector fund		21		1		-		22
			Investment grade corporate sector fund		283		33		-		316
			High-yield sector fund		38		7		-		45
			Real return sector fund		275		-		(1)		274
			Mortgage sector fund		519		1		-		520
			Asset-backed securities sector fund		40		10		-		50
			Emerging market sector fund		65		1		-		66
			International sector fund		170		2		(1)		171
		Equity mutual fund			217		264		-		481
Total investments in marketable securities				$	5,065	$	333	$	(9)	$	5,389

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
					March 31, 2014				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	$	33	$	(1)	$	-	$	-
			Corporate debt securities			43		(1)		-		-
			Mortgage backed securities:
				U.S. government agency		35		(1)		-		-
	Equity instruments:
		Fixed income mutual funds:
			U.S. government sector fund			270		(2)		-		-
			Real return sector fund			268		(1)		-		-
			Mortgage sector fund			-		-		532		(12)
			International sector fund			138		(1)		-		-
Total investments in marketable securities					$	787	$	(7)	$	532	$	(12)

Schedule of realized gains and losses on sales from AFS

			Years Ended March 31,
(Dollars in millions)			2014		2013		2012
Available-for-sale securities:
	Realized gains on sales	$	59	$	23	$	16
	Realized losses on sales	$	(4)	$	(2)	$	(41)
	Other-than-temporary impairment	$	(55)	$	-	$	-

Summary of Contractual Maturities of Available-for-Sale Securities

		Due in 1 Year or				Due after 1 Year				Due after 5 Years
		Less				through 5 Years				through 10 Years				Due after 10 Years				Total
(Dollars in millions)		Amount		Yield		Amount		Yield		Amount		Yield		Amount		Yield		Amount		Yield
Fair Value of Available-for-Sale Securities:
Debt instruments:
U.S. government and
	agency obligations	$	570	0.13	%	$	59	1.57	%	$	23	1.61	%	$	-	0.00	%	$	652	0.81	%
Municipal debt securities			-	0.00			-	0.00			2	5.58			9	5.57			11	5.58
Certificates of deposit			1,599	0.23			-	0.00			-	0.00			-	0.00			1,599	0.23
Commercial paper			507	0.17			-	0.00			-	0.00			-	0.00			507	0.17
Corporate debt
	securities		2	5.51			63	3.67			64	3.75			40	4.68			169	3.90
Mortgage-backed securities:
	U.S. government agency		-	0.00			1	5.78			3	3.45			56	3.45			60	3.47
	Non-agency residential		-	0.00			-	0.00			-	0.00			5	9.49			5	9.49
	Non-agency commercial		-	0.00			3	2.24			1	3.28			39	3.11			43	3.06
Asset-backed securities			-	0.00			5	0.75			4	1.88			18	2.66			27	2.08
Debt instruments total			2,678	0.20			131	2.59			97	3.20			167	3.87			3,073	0.70
Equity instruments:
Fixed income mutual funds																			1,835	4.41
Equity mutual funds																			481	4.27
Equity instruments total			-				-				-				-				2,316	4.38
Total fair value		$	2,678	0.20	%	$	131	2.59	%	$	97	3.20	%	$	167	3.87	%	$	5,389	2.28	%
Total amortized cost		$	2,679			$	127			$	97			$	164			$	5,065