Trust Assets, Escrow and Other Deposits (Narrative) (Detail) - USD ($) $ in Billions	Sep. 30, 2022	Dec. 31, 2021
Other Assets [Line Items]
Escrow deposits	$ 11.7	$ 10.8
Like-kind exchange funds	4.1	6.0
Cash deposits	1.7
Cash deposits with third party financial institutions		0.4
First American Trust
Other Assets [Line Items]
Escrow deposits	5.5	4.8
Assets held-in-trust	3.9	$ 4.6
Cash deposits	$ 0.9