v3.26.1
Summary of accounting policies - Additional information (Detail)
12 Months Ended
Mar. 31, 2026
Segment
Accounting Policy [Line Items]  
Number of business segments 4
Minimum [Member] | Equity investments [Member]  
Accounting Policy [Line Items]  
Ownership percentage 20.00%
Maximum [Member] | Equity investments [Member]  
Accounting Policy [Line Items]  
Ownership percentage 50.00%
Limited partnership [Member] | Minimum [Member] | Equity investments [Member]  
Accounting Policy [Line Items]  
Ownership percentage 3.00%