Borrowings - Additional Information (Detail) - USD ($)		12 Months Ended
	Jan. 31, 2006	Dec. 31, 2020	Dec. 31, 2006	Dec. 31, 2019
Debt Instrument [Line Items]
Funds borrowed under repurchase agreement		$ 439,406,000		$ 428,659,000
Weighted average interest rates		0.10%		0.44%
Loans at carrying value		$ 6,070,000,000.00		$ 6,030,000,000.00
Investment securities at carrying value		1,810,000,000		1,640,000,000
Period of LIBOR	1 year
Short term borrowings		5,000,000.0		$ 0
Collateral Pledged [Member]
Debt Instrument [Line Items]
Investment securities at carrying value		$ 1,810,000,000
CVB Statutory Trust III [Member] | Junior Subordinated Debenture Held by CVB Statutory Trust III [Member]
Debt Instrument [Line Items]
Trust preferred securities, offered fair value	$ 25,000,000
Proceeds from the offering and other cash	$ 25,774,000
Maximum Period of Deferred payments of interest		20 consecutive quarters
Trust Preferred Securities, maturity date		Mar. 15, 2036
Trust Preferred Securities, interest rate in excess of LIBOR			1.38%
Trust Preferred Securities callable date		Mar. 15, 2011