Restructuring, Impairment and Related Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Restructuring Cost and Reserve [Line Items]
Net restructuring, impairment and related charges recognized	$ 60	$ 45	$ 116	$ 68
Restructuring liabilities	155		155		$ 157
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	90		90
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	90		90
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	125		125
Operating Model and Cost Optimization Programs
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	271		271
Operating Model and Cost Optimization Programs | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	300		300
Operating Model and Cost Optimization Programs | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	320		320
Strategic Growth Initiative Plan | International
Restructuring Cost and Reserve [Line Items]
Net restructuring, impairment and related charges recognized	27		41
Strategic Growth Initiative Plan | Minimum | International
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	100		100
Strategic Growth Initiative Plan | Maximum | International
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	$ 120		$ 120