Contract Receivables, Net - Summary of Reconciliation of Billed Contract Receivables Sold to MUF Including Receivables Sold to MUFC And Collected from Customers on Behalf of MUFG And Receivables Not Yet Collected from Customers (Parenthetical) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Receivables [Abstract]
Proceeds from sale of billed contract receivables	$ 9.4	$ 27.9