Share-based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Mar. 31, 2020 USD ($) $ / shares shares
Shares
Outstanding at beginning of year (in shares) | shares	162
Exercised (in shares) | shares	(57)
Forfeited (in shares) | shares	(3)
Outstanding, vested and exercisable at end of year (in shares) | shares	102
Weighted Average Exercise Price Per Share
Outstanding at beginning of year (in dollars per share) | $ / shares	$ 12
Exercised (in dollars per share) | $ / shares	10
Forfeited (in dollars per share) | $ / shares	11
Outstanding, vested and exercisable at end of year (in dollars per share) | $ / shares	$ 13
Weighted Average Remaining Contractual Term in Years	2 years 8 months 12 days
Intrinsic Value | $	$ 520