Loans Receivable - Nonaccrual Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	$ 44,536	$ 13,703
Commercial business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	44,331	12,564
Commercial business | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	33,547	6,639
Commercial business | Owner-occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	4,715	4,212
Commercial business | Non-owner occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	6,069	1,713
One-to-four family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	19	71
Real estate construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	0	899
Real estate construction and land development | One-to-four family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	0	899
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross nonaccrual loans	$ 186	$ 169