Stock Incentive Plans - Schedule of Options (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017
Additional Disclosures
Aggregate Intrinsic Value (in millions) - Exercised	$ 45	$ 10	$ 74	$ 54
Stock Options
Number of Option Shares
Outstanding beginning of period (in shares)			4,767,396
HPE options converted to DXC options at Merger (in shares)			2,654,872
CSC Options Converted to RSU's due to Merger (in shares)			(1,521,519)
Exercised (in shares)			(1,818,441)
Canceled/Forfeited (in shares)			(1,214)
Expired (in shares)			(35,987)
Outstanding end of period (in shares)	4,045,107		4,045,107		4,767,396
Weighted Average Exercise Price
Weighted Average Exercise Price - beginning of period (in dollars per share)			$ 38.70
Weighted Average Exercise Price - HPE options converted to DXC options at Merger (in dollars per share)			46.56
Weighted Average Exercise Price - CSC Options converted to RSU's due to merger (in dollars per share)			51.00
Weighted Average Exercise Price - Exercised (in dollars per share)			39.10
Weighted Average Exercise Price - Cancelled/Forfeited (in dollars per share)			68.20
Weighted Average Exercise Price - Expired (in dollars per share)			43.23
Weighted Average Exercise Price - end of period (in dollars per share)	$ 39.01		$ 39.01		$ 38.70
Additional Disclosures
Weighted Average Remaining Contractual Term (in years)			5 years 9 months 29 days		8 years 4 days
Aggregate Intrinsic Value (in millions)	$ 190		$ 190		$ 145
Aggregate Intrinsic Value (in millions) - Exercised			$ 74
Vested and Expected to Vest
Vested and expected to vest in the future as of period end (in shares)	4,037,125		4,037,125
Exercisable as of period end (in shares)	3,992,228		3,992,228
Weighted average exercise price vested and expected to vest as of period end (in dollars per share)	$ 38.96		$ 38.96
Weighted average exercise price exercisable as of period end (in dollars per share)	$ 38.70		$ 38.70
Weighted average remaining contractual life vested and expected to vest in the future as of period end (in years)			5 years 9 months 29 days
Weighted average remaining contractual life exercisable as of period end (in years)			5 years 9 months 21 days
Aggregate intrinsic value vested and expected to vest in the future as of period end	$ 189		$ 189
Aggregate intrinsic value exercisable as of period end	$ 188		$ 188