Restructuring, Impairment and Related Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020
Restructuring Cost and Reserve [Line Items]
Net restructuring, impairment and related charges recognized	$ 56	$ 23
Restructuring liabilities	168		$ 157
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	83
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	90
Strategic Growth Initiative Plan - Relocation of Corporate Headquarters | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	125
Operating Model and Cost Optimization Programs
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	245
Operating Model and Cost Optimization Programs | European Pharmaceutical Solutions
Restructuring Cost and Reserve [Line Items]
Pre-tax charges recorded to-date	14
Operating Model and Cost Optimization Programs | Minimum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	290
Operating Model and Cost Optimization Programs | Minimum | European Pharmaceutical Solutions
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	90
Operating Model and Cost Optimization Programs | Maximum
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	320
Operating Model and Cost Optimization Programs | Maximum | European Pharmaceutical Solutions
Restructuring Cost and Reserve [Line Items]
Expected total pre-tax charges	$ 110