Employee Benefit Plans (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) hour	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Percentage of employer contribution fully vested	100.00%
Accrued expenses and other liabilities | Washington Banking
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Carrying value of obligation	$ 200,000	$ 268,000
401(k) Plan and Trust Salary Saving Plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer matching contribution, percent of employee's gross pay	50.00%
Maximum annual contributions per employee, percent	3.00%
Defined contribution plan, employer matching contribution amount	$ 1,600,000	1,400,000	$ 1,100,000
401(k) Plan and Trust
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Minimum hours of service required for eligibility under the plan | hour	1,000
Minimum age required for eligibility under the plan	18 years
Employer profit sharing contributions	$ 0	$ 0	$ 0