Subordinated Debentures - Narrative (Details)			1 Months Ended		12 Months Ended
	Jun. 01, 2020 USD ($)	Nov. 01, 2017 USD ($) note	Jun. 30, 2020 USD ($)	May 31, 2019 USD ($)	Dec. 31, 2020 USD ($) subsidiary loan	Dec. 31, 2019 USD ($)	Apr. 01, 2017 USD ($)	Aug. 31, 2014 USD ($)
Debt Instrument [Line Items]
Subordinated debentures					$ 501,511,000	$ 215,145,000
Increase to carrying value of subordinated debt					286,400,000
Debt issued					$ 505,403,000
Number of trust subsidiaries | subsidiary					2
Opus
Debt Instrument [Line Items]
Subordinated debt	$ 138,653,000
Subordinated notes
Debt Instrument [Line Items]
Number of subordinated debt instruments | loan					5
Subordinated debentures					$ 493,410,000	207,187,000
Debt issued					$ 495,000,000
Subordinated notes | Heritage Oaks Bank
Debt Instrument [Line Items]
Effective rate (as a percent)					1.945%
Purchase accounting fair value adjustments					$ (1,100,000)
Subordinated debt					4,100,000
Subordinated notes | Santa Lucia Bancorp (CA) Capital Trust
Debt Instrument [Line Items]
Subordinated debentures					$ 4,000,000.0
Effective rate (as a percent)					1.72%
Purchase accounting fair value adjustments					$ (1,200,000)
Subordinated notes | Opus
Debt Instrument [Line Items]
Purchase accounting fair value adjustments					3,400,000
Subordinated notes | Subordinated notes due 2030, 5.375% per annum until June 15, 2025, 3-month SOFR +5.17% thereafter
Debt Instrument [Line Items]
Subordinated debentures					147,501,000	0
Debt issued			$ 150,000,000.0		$ 150,000,000
Fixed interest rate (as a percent)			5.375%		5.375%
Unamortized debt issuance costs					$ 2,500,000
Offering price, percentage of aggregate principal amount			100.00%
Subordinated notes | Subordinated notes due 2030, 5.375% per annum until June 15, 2025, 3-month SOFR +5.17% thereafter | SOFR
Debt Instrument [Line Items]
Floating interest rate, basis points added to base rate (as a percent)			5.17%		0.0517%
Subordinated notes | Subordinated notes due 2026, 5.5% per annum until June 30 2021, 3-month LIBOR +4.285% thereafter
Debt Instrument [Line Items]
Subordinated debentures					$ 138,371,000	0
Debt issued	$ 135,000,000.0				$ 135,000,000
Fixed interest rate (as a percent)	5.50%				5.50%
Subordinated notes | Subordinated notes due 2026, 5.5% per annum until June 30 2021, 3-month LIBOR +4.285% thereafter | LIBOR
Debt Instrument [Line Items]
Floating interest rate, basis points added to base rate (as a percent)	4.285%				0.00043%
Subordinated notes | Subordinated notes due 2026, 5.5% per annum until June 30 2021, 3-month LIBOR +4.285% thereafter | Opus
Debt Instrument [Line Items]
Subordinated debentures					$ 138,400,000
Subordinated notes | Subordinated notes due 2024, 5.75% per annum
Debt Instrument [Line Items]
Subordinated debentures					59,552,000	59,432,000
Debt issued					$ 60,000,000			$ 60,000,000.0
Fixed interest rate (as a percent)					5.75%			5.75%
Unamortized debt issuance costs					$ 448,000
Percentage of Notes I qualified as Tier 2 Capital as remaining maturity is less than four years					60.00%
Percentage of Notes I qualified as Tier 2 Capital as remaining maturity is less than five years					80.00%
Subordinated notes | Subordinated notes due 2029, 4.875% per annum until May 15, 2024, 3-month LIBOR +4.9% thereafter
Debt Instrument [Line Items]
Subordinated debentures					$ 122,877,000	122,622,000
Debt issued				$ 125,000,000.0	$ 125,000,000
Fixed interest rate (as a percent)				4.875%	4.875%
Unamortized debt issuance costs					$ 2,100,000
Public offering price				100.00%
Subordinated notes | Subordinated notes due 2029, 4.875% per annum until May 15, 2024, 3-month LIBOR +4.9% thereafter | LIBOR
Debt Instrument [Line Items]
Floating interest rate, basis points added to base rate (as a percent)				2.50%	4.90%
Subordinated notes | Subordinated notes due 2025, 7.125% per annum
Debt Instrument [Line Items]
Subordinated debentures					$ 25,109,000	25,133,000
Debt issued		$ 25,000,000.0			$ 25,000,000
Fixed interest rate (as a percent)		7.125%			7.125%
Purchase accounting fair value adjustments					$ 109,000
Number of subordinated notes assumed | note		3
Redemption price (as a percent)		103.00%
Redemption price, subsequent reduction (as a percent)		0.50%
Carrying value of subordinated notes					$ 25,100,000
Subordinated debt
Debt Instrument [Line Items]
Number of subordinated debt instruments | loan					2
Subordinated debentures					$ 8,101,000	7,958,000
Debt issued					10,403,000
Subordinated debt | Heritage Oaks Bank
Debt Instrument [Line Items]
Subordinated debentures					4,121,000	4,054,000
Debt issued					$ 5,248,000		$ 5,200,000
Effective rate (as a percent)					1.95%
Subordinated debt | Santa Lucia Bancorp (CA) Capital Trust
Debt Instrument [Line Items]
Subordinated debentures					$ 3,980,000	$ 3,904,000
Debt issued					$ 5,155,000
Effective rate (as a percent)					1.72%
Subordinated debt | LIBOR | Heritage Oaks Bank
Debt Instrument [Line Items]
Floating interest rate, basis points added to base rate (as a percent)					1.72%
Subordinated debt | LIBOR | Santa Lucia Bancorp (CA) Capital Trust
Debt Instrument [Line Items]
Floating interest rate, basis points added to base rate (as a percent)					1.48%