Revenue from Contracts with Customers 1 (Details) - USD ($) $ in Millions		3 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
Disaggregation of revenue
Total revenue		$ 938	$ 1,025
Mainframe Solutions
Disaggregation of revenue
Total revenue		440
Enterprise Solutions
Disaggregation of revenue
Total revenue		430
Services
Disaggregation of revenue
Total revenue		68
Point-in-Time, Including Professional Services
Disaggregation of revenue
Total revenue		337
Over Time
Disaggregation of revenue
Total revenue		601
Perpetual Licenses
Disaggregation of revenue
Total revenue		76
On-Premise Term Licenses
Disaggregation of revenue
Total revenue		193
Maintenance
Disaggregation of revenue
Total revenue		487
SaaS
Disaggregation of revenue
Total revenue		114
Professional Services
Disaggregation of revenue
Total revenue		68	$ 75
United States
Disaggregation of revenue
Total revenue		572
EMEA
Disaggregation of revenue
Total revenue	[1]	229
Other
Disaggregation of revenue
Total revenue		$ 137

[1] Consists of Europe, the Middle East and Africa.