Derivative Instruments - Narrative (Details) - USD ($)	3 Months Ended			9 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Oct. 31, 2018	Mar. 31, 2018
Derivative [Line Items]
Cash flow hedge adjustments, net of tax	$ (18,000,000)		$ 0	$ (13,000,000)	$ 0
Interest Rate Swap
Derivative [Line Items]
Pre-tax impact of gain (loss) on derivatives	(25,000,000)			(18,000,000)
Cash flow hedge adjustments, net of tax	(18,000,000)			(13,000,000)
Interest Rate Swap | Interest Expense
Derivative [Line Items]
Gain on cash flow hedge ineffectiveness		$ 5,000,000
Derivatives Designated for Hedge Accounting | Interest Rate Swap
Derivative [Line Items]
Foreign currency cash flow hedge gain to be reclassified during next 12 months	3,000,000			3,000,000
Derivative liability, fair value	13,000,000			13,000,000
Derivatives Designated for Hedge Accounting | Interest Rate Swap | Accrued Expenses and Other Current Liabilities
Derivative [Line Items]
Derivative liability, fair value	2,000,000			2,000,000
Derivatives Designated for Hedge Accounting | Interest Rate Swap | Other Liabilities
Derivative [Line Items]
Derivative liability, fair value	11,000,000			11,000,000
Derivatives Designated for Hedge Accounting | Cash Flow Hedging | Interest Rate Swap
Derivative [Line Items]
Derivative notional amount	$ 1,600,000,000			$ 1,600,000,000		$ 200,000,000	$ 1,400,000,000