Contingencies (Judgments Paid and Provisions for Tobacco and Health Litigation) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended	162 Months Ended
	May 31, 2001	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2015	Mar. 31, 2018
Loss Contingency Accrual [Roll Forward]
Accrued liability for tobacco and health litigation items at beginning of period		$ 106	$ 47
Payments		(23)	(1)
Accrued liability for tobacco and health litigation items at end of period		111	47		$ 111
Interest Expense Related To Litigation [Member]
Loss Contingency Accrual [Roll Forward]
Pre-tax charges		4	0
Tobacco and Health Judgment [Member]
Loss Contingencies [Line Items]
Judgments paid (approximately)					506
Litigation settlement interest expense (income) (approximately)					187
Tobacco and Health Judgment [Member] | Litigation Cases Results [Member]
Loss Contingency Accrual [Roll Forward]
Pre-tax charges		24	$ 1
Engle Progeny Cases [Member]
Loss Contingencies [Line Items]
Judgments paid (approximately)					114
Litigation settlement interest expense (income) (approximately)					25
PM USA [Member] | Engle Progeny Cases [Member]
Loss Contingencies [Line Items]
Payments made (approximately)	$ 500
PM USA [Member] | Engle Progeny Cases, Federal [Member]
Loss Contingencies [Line Items]
Payments made (approximately)				$ 43	43
Other Assets [Member] | Pending Litigation [Member] | PM USA [Member]
Loss Contingency Accrual [Roll Forward]
Security posted for appeal of judgments (approximately)		$ 98			$ 98