Contingencies (Non-Engle Progeny Litigation) (Details) - USD ($) $ in Millions	Feb. 29, 2020	Sep. 30, 2019	Aug. 31, 2019	Oct. 31, 2017
Non-Engle Progeny Smoking And Health Case, Principe [Member]
Loss Contingencies [Line Items]
Compensatory damages awarded	$ 11.0
Non-Engle Progeny Smoking and Health Case, Greene [Member]
Loss Contingencies [Line Items]
Compensatory damages awarded		$ 10.0
Non-Engle Progeny Smoking and Health Case, Laramie [Member]
Loss Contingencies [Line Items]
Compensatory damages awarded			$ 11.0
Punitive damages awarded			$ 10.0
Non-Engle Progeny Smoking and Health Case, Gentile [Member]
Loss Contingencies [Line Items]
Compensatory damages awarded				$ 7.1
Non-Engle Progeny Smoking and Health Case, Gentile [Member] | PM USA [Member]
Loss Contingencies [Line Items]
Compensatory damages awarded				$ 5.3
Compensatory damages award, allocation percentage				75.00%