Restructuring and Asset Impairment Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Pre-tax restructuring and asset impairment charges	$ 23	$ 96
After-tax restructuring and asset impairment charges	17	85
Pre-tax impairment charge		20
After-tax impairment charges		16
Strategic Growth Initiative Plan
Restructuring Cost and Reserve [Line Items]
Net restructuring charges recognized	4
Net restructuring charges recognized, after tax	3
Pre-tax charges recorded to-date	139
Strategic Growth Initiative Plan | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	140
Strategic Growth Initiative Plan | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	180
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	41
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Employee retention
Restructuring Cost and Reserve [Line Items]
Net restructuring charges recognized	8
Net restructuring charges recognized, after tax	6
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	80
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	130
Strategic Growth Initiative Plan - Other
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	174
Strategic Growth Initiative Plan - Other | Project consulting fee
Restructuring Cost and Reserve [Line Items]
Net restructuring charges recognized	11
Net restructuring charges recognized, after tax	8
Strategic Growth Initiative Plan - Other | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	300
Strategic Growth Initiative Plan - Other | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	350
Fiscal 2019 Initiatives
Restructuring Cost and Reserve [Line Items]
Net restructuring charges recognized	23	$ 69
Restructuring liabilities	133		$ 150
Fiscal 2019 Initiatives | Other accrued liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	107		117
Fiscal 2019 Initiatives | Other noncurrent liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	26		33
Other plans
Restructuring Cost and Reserve [Line Items]
Restructuring liabilities	$ 60		$ 87