Revenue Recognition - Impact of Adoption (Details) - USD ($) $ in Millions			3 Months Ended				6 Months Ended
	Oct. 01, 2019	Oct. 01, 2018	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
ASSETS
Accounts receivable, net			$ 262				$ 262		$ 314
Inventory			56				56		63
Contract assets			233				233		187
Contract costs			130				130		114
Other current assets	$ 113		211				211		115
Property, plant and equipment, net			254				254		255
Deferred income taxes, net			27				27		35
Other assets			114				114		121
Accounts Payable, Current			254				254		291
LIABILITIES
Contract liabilities			477				477		472
Other current liabilities			246				246		158
Deferred income taxes, net			48				48		72
Other liabilities	313		313				313		316
STOCKHOLDERS' EQUITY
Retained Earnings (Accumulated Deficit)			(1,015)				(1,015)		$ (289)
REVENUE
Revenue			(682)		$ (709)		(1,397)	$ (1,447)
Contract with Customer, Liability, Revenue Recognized	$ 405	$ 396
COSTS
Cost of Revenue			311		323		632	654
GROSS PROFIT			(371)		(386)		(765)	(793)
Operating Income (Loss) [Abstract]
OPERATING LOSS			597		(38)		582	(88)
Interest expense			(53)		(58)		(111)	(118)
Other income (expense), net			(15)		(1)		(29)	(23)
LOSS BEFORE INCOME TAXES			(635)		(19)		(664)	(7)
(Provision for) benefit from income taxes			37		(6)		62	(3)
Net income (loss)			(672)	$ (54)	(13)	$ 9	(726)	(4)
Products
REVENUE
Revenue			(245)		(287)		(543)	(611)
COSTS
Total Cost of Goods and Services			(92)		(105)		(196)	(220)
Amortization of technology intangible assets			(44)		(44)		(87)	(87)
Services
REVENUE
Revenue			(437)		(422)		(854)	(836)
COSTS
Total Cost of Goods and Services			$ (175)		$ (174)		$ (349)	$ (347)