Pension and Other Postretirement Benefits (Tables)

12 Months Ended

Apr. 30, 2012

Pension and Other Postretirement Benefits [Abstract]

Change in present value of pension and other postretirement benefit obligation

	Pension Benefits						Medical and Life Insurance Benefits
	2011			2012			2011			2012
Obligation at beginning of year	$	577		$	613		$	58		$	56
Service cost		16			16			1			2
Interest cost		33			34			3			3
Net actuarial loss (gain)		10			89			(10	)		4
Plan amendments		—			1			6			—
Retiree contributions		—			—			2			2
Benefits paid		(24	)		(26	)		(4	)		(5	)
Special termination benefits		1			—			—			—
Obligation at end of year	$	613		$	727		$	56		$	62

Expected benefit payments over the next 10 years

	Pension Benefits		Medical and Life Insurance Benefits
2013	$	27	$	3
2014		28		3
2015		29		3
2016		31		3
2017		32		3
2018–2022		194		18

Fair value of pension plan assets by category, as well as the actual and target allocations

									Allocation by Asset Class
	Level 1		Level 2		Level 3		Total		Actual			Target
April 30, 2011:
Commingled trust funds (a):
Equity funds	$	—	$	232	$	—	$	232		50	%		47	%
Fixed income funds		—		166		—		166		35	%		35	%
Real estate funds		—		18		9		27		6	%		8	%
Total commingled trust funds		—		416		9		425		91	%		90	%
Hedge funds (b)		—		—		24		24		5	%		5	%
Private equity (c)		—		—		16		16		3	%		5	%
Cash and temporary investments (d)		2		—		—		2		1	%		—
Total	$	2	$	416	$	49	$	467		100	%		100	%
April 30, 2012:
Commingled trust funds:
Equity funds	$	—	$	239	$	—	$	239		47	%		47	%
Fixed income funds		—		181		—		181		35	%		35	%
Real estate funds		—		19		26		45		9	%		8	%
Total commingled trust funds		—		439		26		465		91	%		90	%
Hedge funds		—		—		24		24		5	%		5	%
Private equity		—		—		17		17		3	%		5	%
Cash and temporary investments		2		—		—		2		1	%		—
Total	$	2	$	439	$	67	$	508		100	%		100	%

(a) Commingled trust fund valuations are based on the net asset value (NAV) of the funds as determined by the administrator of the fund and reviewed by us. NAV represents the underlying assets owned by the fund, minus liabilities and divided by the number of shares or units outstanding.

(b) Hedge fund valuations are based primarily on the NAV of the funds as determined by fund administrators and reviewed by us. During our review, we determine whether it is necessary to adjust a valuation for inherent liquidity and redemption issues that may exist within a fund’s underlying assets or fund unit values.

(c) As of April 30, 2011 and 2012, consists only of limited partnership interests, which are valued at the percentage ownership of total partnership equity as determined by the general partner. These valuations require significant judgment due to the absence of quoted market prices, the inherent lack of liquidity, and the long-term nature of these investments.

(d) Cash and temporary investments consist of money market funds and are valued at their respective NAVs as determined by those funds each business day.

Change in fair value of Level 3 assets

	Real Estate			Hedge			Private
	Funds			Funds			Equity			Total
Balance as of May 1, 2010	$	10		$	19		$	13		$	42
Return on assets held at end of year		2			1			1			4
Return on assets sold during year		—			(1	)		—			(1	)
Purchases and settlements		—			6			4			10
Sales and settlements		(3	)		(1	)		(2	)		(6	)
Balance as of April 30, 2011		9			24			16			49
Return on assets held at end of year		3			(1	)		—			2
Return on assets sold during year		—			1			—			1
Purchases and settlements		14			—			3			17
Sales and settlements		—			—			(2	)		(2	)
Balance as of April 30, 2012	$	26		$	24		$	17		$	67

Change in fair value of pension plan Assets

	Pension						Medical and Life
	Benefits						Insurance Benefits
	2011			2012			2011			2012
Fair value at beginning of year	$	351		$	467		$	—		$	—
Actual return on plan assets		64			27			—			—
Retiree contributions		—			—			2			2
Company contributions		76			40			2			3
Benefits paid		(24	)		(26	)		(4	)		(5	)
Fair value at end of year	$	467		$	508		$	—		$	—

Funded status of plans

	Pension						Medical and Life
	Benefits						Insurance Benefits
	2011			2012			2011			2012
Assets	$	467		$	508		$	—		$	—
Obligations		(613	)		(727	)		(56	)		(62	)
Funded status	$	(146	)	$	(219	)	$	(56	)	$	(62	)

Funded status is recorded on the accompanying consolidated balance sheets

	Pension						Medical and Life
	Benefits						Insurance Benefits
	2011			2012			2011			2012
Other assets	$	7		$	3		$	—		$	—
Accounts payable and accrued expenses		(3	)		(3	)		(3	)		(3	)
Accrued postretirement benefits		(150	)		(219	)		(53	)		(59	)
Net liability	$	(146	)	$	(219	)	$	(56	)	$	(62	)
Accumulated other comprehensive loss:
Net actuarial loss (gain)	$	263		$	346		$	(3	)	$	1
Prior service cost		3			4			6			6
	$	266		$	350		$	3		$	7

Pension plans that have assets in excess of their accumulated benefit obligations with those whose assets are less than their obligations

	Plan Assets				Accumulated Benefit Obligation				Projected Benefit Obligation
	2011		2012		2011		2012		2011		2012
Plans with assets in excess of accumulated benefit obligation	$	50	$	49	$	41	$	45	$	42	$	46
Plans with accumulated benefit obligation in excess of assets		417		459		505		598		571		681
Total	$	467	$	508	$	546	$	643	$	613	$	727

Pension Expense

	Pension Benefits
	2010			2011			2012
Service cost	$	10		$	16		$	16
Interest cost		32			33			34
Special termination benefits		—			1			—
Expected return on plan assets		(34	)		(36	)		(40	)
Amortization of:
Prior service cost		1			1			1
Net actuarial loss		4			18			19
Net expense	$	13		$	33		$	30

Postretirement medical and life insurance benefit expense

	Medical and Life Insurance Benefits
	2010		2011		2012
Service cost	$	1	$	1	$	2
Interest cost		3		3		3
Net expense	$	4	$	4	$	5

Amounts recognized in other comprehensive income

	Pension Benefits									Medical and Life Insurance Benefits
	2010			2011			2012			2010		2011			2012
Prior service cost	$	—		$	—		$	1		$	—	$	5		$	—
Actuarial loss (gain)		100			(18	)		102			12		(10	)		4
Amortization reclassified to net income:
Prior service cost		(1	)		(1	)		(1	)		—		—			—
Net actuarial loss		(4	)		(18	)		(19	)		—		—			—
Net amount recognized in other comprehensive income (loss)	$	95		$	(37	)	$	83		$	12	$	(5	)	$	4

Assumptions used in computing benefit plan obligations

	Pension Benefits						Medical and Life Insurance Benefits
	2011			2012			2011			2012
Discount rate		5.67	%		4.92	%		5.59	%		4.84	%
Rate of salary increase		4.00	%		4.00	%		n/a			n/a

Assumptions used in computing benefit plan expense

	Pension Benefits									Medical and Life Insurance Benefits
	2010			2011			2012			2010			2011			2012
Discount rate		7.94	%		5.91	%		5.67	%		7.80	%		5.78	%		5.59	%
Rate of salary increase		4.00	%		4.00	%		4.00	%		n/a			n/a			n/a
Expected return on plan assets		8.50	%		8.50	%		8.25	%		n/a			n/a			n/a

Assumed health care cost trend rates

	Medical and Life Insurance Benefits
	2011			2012
Health care cost trend rate assumed for next year:
Present rate before age 65		7.5	%		8.0	%
Present rate age 65 and after		7.5	%		8.0	%