Revenue - Schedule of Estimated Technology Services and Subscription Revenue Expected to Be Recognized in Future, Related to Unsatisfied Portion of Performance Obligations (Detail) - Technology Services and Subscription Revenue [Member] - USD ($) $ in Millions	Mar. 31, 2025	Mar. 31, 2024
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation	$ 480	$ 303
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-04-01
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period		9 months
Revenue, Remaining Performance Obligation		$ 104
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period		1 year
Revenue, Remaining Performance Obligation		$ 76
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-04-01
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months
Revenue, Remaining Performance Obligation	$ 177
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year	1 year
Revenue, Remaining Performance Obligation	$ 141	$ 59
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year	1 year
Revenue, Remaining Performance Obligation	$ 73	$ 33
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-01-01
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year	1 year
Revenue, Remaining Performance Obligation	$ 38	$ 31
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2029-01-01
Schedule of Investment Advisory Administration Fees and Securities Lending Revenue and Performance Fees by Type [line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation	$ 51