Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) Subsidiary Trust	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of inactive subsidiaries acquired | Subsidiary		4
Number of statutory business trusts acquired | Trust		2
Cash and due from banks, reserves required to be held		$ 29,500,000	$ 24,500,000
Debt securities evaluation for other-than-temporary impairment, measurement basis		quarterly
Threshold period past due principal or interest, to discontinue accrual of interest on loans		90 days
Gain on sale of loans		$ 9,893,000	7,126,000	$ 9,318,000
Gains on sale of mortgage loans, total		8,200,000	4,300,000	3,700,000
Gains on sale of SBA loans, total		1,500,000	2,800,000	5,600,000
Gains on sale of CRE, total		152,000	0	0
Goodwill		58,563,000	58,383,000
Impairment losses recognized on goodwill		0	0
Amortization of intangibles		4,856,000	3,302,000	1,845,000
Total gross loans		$ 2,300,000,000
Percentage of gross loans with LIBOR based reference rate		25.00%
Out-of-Scope Topic 606
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of non interest income		79.00%
ASU 2014-09
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of non interest income		21.00%
401(k) Plan
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Contributions to plan		$ 570,000	341,000	272,000
CRA Investments
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Carrying amount of equity securities without readily determinable fair values		11,800,000	10,000,000
Pacific Coast Bankers' Bank
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Carrying amount of equity securities without readily determinable fair values		324,000
Estimated gain on equity securities	$ 107,000
Atlantic Community Bankers’ Bank
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Carrying amount of equity securities without readily determinable fair values		100,000
Estimated gain on equity securities	$ 40,000
Core Deposit Intangible
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Unamortized balance of intangible assets		6,100,000	7,600,000
Accumulated amortization		3,100,000	1,600,000
Amortization of intangibles		$ 1,500,000	575,000	355,000
Premises
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets		30 years
Mortgage, SBA and CRE
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Gain on sale of loans		$ 9,900,000	$ 7,100,000	$ 9,300,000
Minimum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Right-of-use asset		25,000,000
Lease liability		$ 25,000,000
Minimum | Core Deposit Intangible
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, estimated useful life		8 years
Minimum | Leasehold Improvements
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets		3 years
Minimum | Equipment
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets		3 years
Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents maturity period		90 days
Right-of-use asset		$ 30,000,000
Lease liability		$ 30,000,000
Maximum | Core Deposit Intangible
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, estimated useful life		10 years
Maximum | Leasehold Improvements
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets		10 years
Maximum | Equipment
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets		10 years