Segment Information (Long-Lived Assets By Geographic Area) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 434	$ 439
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	369	368
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 65	$ 71