Condensed Consolidated Statements of Stockholders' Equity Statement - USD ($) shares in Thousands, $ in Millions	Total		Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (loss)
Beginning balance (in shares) at Mar. 31, 2020			288,413
Beginning balance at Mar. 31, 2020	$ 7,461		$ 3	$ 0	$ 7,508	$ (50)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	363				365	(2)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	102			102
Stock Issued During Period, Shares, New Issues			1,088
Stock Issued During Period, Value, New Issues	(66)			(66)
Stock Repurchased and Retired During Period, Shares			(747)
Stock Repurchased and Retired During Period, Value	(78)			(36)	(42)
Ending balance (in shares) at Jun. 30, 2020			288,754
Ending balance at Jun. 30, 2020	7,782		$ 3	0	7,831	(52)
Beginning balance (in shares) at Mar. 31, 2020			288,413
Beginning balance at Mar. 31, 2020	7,461		$ 3	0	7,508	(50)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss) before reclassifications	(33)
Amounts reclassified from accumulated other comprehensive income (loss)	(6)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	511
Ending balance (in shares) at Sep. 30, 2020			289,622
Ending balance at Sep. 30, 2020	8,075		$ 3	145	8,016	(89)
Beginning balance (in shares) at Jun. 30, 2020			288,754
Beginning balance at Jun. 30, 2020	7,782		$ 3	0	7,831	(52)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss) before reclassifications	(36)
Amounts reclassified from accumulated other comprehensive income (loss)	(1)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	148				185	(37)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	113			113
Stock Issued During Period, Shares, New Issues			868
Stock Issued During Period, Value, New Issues	32			32
Stock Repurchased and Retired During Period, Shares			0
Stock Repurchased and Retired During Period, Value	0			0	0
Ending balance (in shares) at Sep. 30, 2020			289,622
Ending balance at Sep. 30, 2020	$ 8,075		$ 3	145	8,016	(89)
Beginning balance (in shares) at Mar. 31, 2021	286,000		286,465
Beginning balance at Mar. 31, 2021	$ 7,840	[1]	$ 3	0	7,887	(50)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	219				204	15
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	125			125
Stock Issued During Period, Value, Acquisitions	23			23
Stock Issued During Period, Shares, New Issues			1,209
Stock Issued During Period, Value, New Issues	(105)			(105)
Stock Repurchased and Retired During Period, Shares			(2,292)
Stock Repurchased and Retired During Period, Value	(325)			(43)	(282)
Cash dividends declared ($0.17 per common share)	(49)				(49)
Ending balance (in shares) at Jun. 30, 2021			285,382
Ending balance at Jun. 30, 2021	$ 7,728		$ 3	0	7,760	(35)
Beginning balance (in shares) at Mar. 31, 2021	286,000		286,465
Beginning balance at Mar. 31, 2021	$ 7,840	[1]	$ 3	0	7,887	(50)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss) before reclassifications	23
Amounts reclassified from accumulated other comprehensive income (loss)	25
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 546
Common Stock, Dividends, Per Share, Declared	$ 0.17
Ending balance (in shares) at Sep. 30, 2021	284,000		283,666
Ending balance at Sep. 30, 2021	$ 7,856		$ 3	0	7,855	(2)
Beginning balance (in shares) at Jun. 30, 2021			285,382
Beginning balance at Jun. 30, 2021	7,728		$ 3	0	7,760	(35)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss) before reclassifications	19
Amounts reclassified from accumulated other comprehensive income (loss)	14
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	327				294	33
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	149			149
Stock Issued During Period, Shares, New Issues			602
Stock Issued During Period, Value, New Issues	25			25
Stock Repurchased and Retired During Period, Shares			(2,318)
Stock Repurchased and Retired During Period, Value	(325)			(174)	(151)
Cash dividends declared ($0.17 per common share)	$ (48)				(48)
Ending balance (in shares) at Sep. 30, 2021	284,000		283,666
Ending balance at Sep. 30, 2021	$ 7,856		$ 3	$ 0	$ 7,855	$ (2)

[1] Derived from audited Consolidated Financial Statements.