Debt and Credit Facilities (Tables)

12 Months Ended

Apr. 30, 2017

Debt Disclosure [Abstract]

Schedule of long-term debt

Our long-term debt (net of unamortized discounts and issuance costs) consisted of:

April 30,	2016		2017
1.00% senior notes, $250 principal amount, due January 15, 2018	$	249	$	249
2.25% senior notes, $250 principal amount, due January 15, 2023	248		248
1.20% senior notes, €300 principal amount, due July 7, 2026	—		324
2.60% senior notes, £300 principal amount, due July 7, 2028	—		383
3.75% senior notes, $250 principal amount, due January 15, 2043	248		248
4.50% senior notes, $500 principal amount, due July 15, 2045	485		486
	1,230		1,938
Less current portion	—		249
	$	1,230	$	1,689