Pension and Other Postretirement Benefits (Change in Fair Value of Pension Plan Assets) (Details) - USD ($) $ in Millions |
12 Months Ended | |
---|---|---|
Apr. 30, 2018 |
Apr. 30, 2017 |
|
Change in fair value of pension plan Assets | ||
Beginning balance | $ 623 | |
Ending balance | 780 | $ 623 |
Pension Benefits [Member] | ||
Change in fair value of pension plan Assets | ||
Beginning balance | 623 | 594 |
Actual return on assets | 53 | 51 |
Retiree contributions | 0 | 0 |
Company contributions | 155 | 31 |
Benefits paid | (51) | (53) |
Ending balance | 780 | 623 |
Medical and Life Insurance Benefits [Member] | ||
Change in fair value of pension plan Assets | ||
Beginning balance | 0 | 0 |
Actual return on assets | 0 | 0 |
Retiree contributions | 1 | 1 |
Company contributions | 3 | 3 |
Benefits paid | (4) | (4) |
Ending balance | $ 0 | $ 0 |