Basis of Presentation Reclassification of prior period amounts (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2018
Reclassification of prior period amounts [Line Items]
Proceeds from Sale and Collection of Receivables	$ 170	$ 375
Net Cash Provided by (Used in) Financing Activities	(295)	(1,363)
Payments to Acquire Equipment on Lease	1,817	1,359
Net Cash Provided by (Used in) Investing Activities	(4,369)	(953)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 4,425	2,550	$ 2,942	$ 6,659
Accounting Standards Update 2016-15 [Member]
Reclassification of prior period amounts [Line Items]
Net Cash Provided by (Used in) Financing Activities		129
Net Cash Provided by (Used in) Investing Activities		(2)
Adjustments for New Accounting Pronouncement [Member]
Reclassification of prior period amounts [Line Items]
Payments to Acquire Equipment on Lease			900
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents			$ 72
Revenue, Equipment Rentals, Net [Member]
Reclassification of prior period amounts [Line Items]
Prior Period Reclassification Adjustment		899
Cost of Equipment Rentals [Member]
Reclassification of prior period amounts [Line Items]
Prior Period Reclassification Adjustment		112
Depreciation - Equipment Rentals [Member]
Reclassification of prior period amounts [Line Items]
Prior Period Reclassification Adjustment		$ 854