Restructuring, Impairment and Related Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring, impairment and related charges	$ 45	$ 82		$ 68	$ 178
After-tax restructuring, impairment and related charges	35	67		52	152
Pre-tax impairment charge			$ 20
After-tax impairment charges			$ 16
Strategic Growth Initiative Plan
Restructuring Cost and Reserve [Line Items]
Net restructuring, impairment and related charges recognized	3			7
Net restructuring, impairment and related charges recognized, after tax	3			6
Pre-tax charges recorded to-date	142			142
Strategic Growth Initiative Plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	140			140
Strategic Growth Initiative Plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	180			180
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	53			53
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Employee retention expenses, asset impairments and accelerated depreciation
Restructuring Cost and Reserve [Line Items]
Net restructuring, impairment and related charges recognized	12			20
Net restructuring, impairment and related charges recognized, after tax	9			15
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	80			80
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	130			130
Strategic Growth Initiative Plan - Other
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	202			202
Strategic Growth Initiative Plan - Other | Project consulting fee
Restructuring Cost and Reserve [Line Items]
Net restructuring, impairment and related charges recognized	28			39
Net restructuring, impairment and related charges recognized, after tax	22			30
Strategic Growth Initiative Plan - Other | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	300			300
Strategic Growth Initiative Plan - Other | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	350			350
Fiscal 2019 Initiatives
Restructuring Cost and Reserve [Line Items]
Net restructuring, impairment and related charges recognized	43	$ 75		66	$ 144
Restructuring liabilities	141			141		$ 150
Fiscal 2019 Initiatives | Other accrued liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	119			119		117
Fiscal 2019 Initiatives | Other noncurrent liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	22			22		33
Other plans
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	$ 48			$ 48		$ 87