Stockholder's Equity - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	[1]
Equity [Abstract]
Preferred stock dividend percentage	6.00%
Ownership percentage of PACCAR	100.00%
Accumulated other comprehensive (loss) income	$ 12.2	$ 11.0

[1] The December 31, 2023 balance sheet has been derived from audited financial statements.