CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Mar. 31, 2020
Current assets:
Allowance for doubtful accounts	$ 91	$ 74
Accumulated amortization	4,422	4,347
Accumulated depreciation	$ 4,121	$ 3,818
CSC stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	750,000,000	750,000,000
Common stock, issued (in shares)	257,052,533	255,674,040
Common stock in treasury, at cost (in shares)	2,458,027	2,148,708