Segment Information (Long-Lived Assets By Geographic Area) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Mar. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 449	$ 448
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	375	371
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 74	$ 77