(Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Millions	6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Accrued Liabilities, Fair Value Disclosure	$ 136
Payments	(64)	$ 0
Accrued Liabilities, Fair Value Disclosure	69
Other liabilities | Fair Value, Inputs, Level 3 [Member] | Contingent consideration
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Accrued Liabilities, Fair Value Disclosure	136
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	3
Payments	70
Accrued Liabilities, Fair Value Disclosure	$ 69