XML 20 R9.htm IDEA: XBRL DOCUMENT v3.21.2
STATEMENTS OF CONSOLIDATED CASH FLOWS (UNAUDITED) (Parenthetical) - Senior Notes
Sep. 30, 2021
May 20, 2021
Sep. 30, 2020
May 01, 2020
Apr. 28, 2020
4.50% Senior Notes          
Debt instrument contractual rate (percent) 4.50% 4.50%      
6.50% Senior Notes          
Debt instrument contractual rate (percent)     6.50% 6.50% 6.50%