Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 21,142	$ 17,447	$ 68,691	$ 43,678
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			3,791	4,063
Deferred taxes			(642)	(2,034)
Stock-based compensation			636	708
Provision for credit losses (recovery)	(163)	2,433	(6,919)	15,091	$ 16,047
Write-downs of other real estate owned and other repossessed assets			637	1,021
Gains on sale of mortgage loans held for sale	(1,239)	(2,470)	(5,579)	(4,706)
Securities gains			(60)	(1,069)
Change in fair market value of equity securities	62	(119)	10	(259)
Gains on sale of assets, net			(223)	(120)
Proceeds from sale of mortgage loans held for sale			250,070	224,796
Funding of mortgage loans held for sale			(233,288)	(239,048)
Amortization of securities premiums and discounts, net			5,977	4,049
Change in cash surrender value of bank owned life insurance			(1,094)	(1,048)
Payment of operating lease liabilities			(1,271)	(1,269)
Mortgage servicing rights:
Fair value adjustments			(380)	1,325
New servicing assets created			(1,817)	(1,171)
Changes in:
Accrued interest receivable			538	122
Other assets			4,125	(3,461)
Accrued interest payable			601	2,340
Other liabilities			(1,869)	(818)
Net cash provided by operating activities			81,934	42,190
Securities available-for-sale (AFS):
Purchase of AFS securities			(795,657)	(645,652)
Proceeds from sales of AFS securities			1,080	82,314
Proceeds from prepayments, calls, and maturities of AFS securities			243,420	222,385
Securities held-to-maturity (HTM):
Proceeds from maturities of HTM securities			0	517
Change in loans, net			156,259	(314,299)
Purchase of premises and equipment			(1,171)	(766)
Proceeds from sale and retirement of premises and equipment			830	0
Proceeds from sale of stock by Federal Home Loan Bank			1,909	351
Proceeds from sale of other real estate owned and repossessed assets			2,556	2,814
Additional investment in bank owned life insurance			(17,825)	0
Net cash used in investing activities			(408,599)	(652,336)
Cash flows from financing activities:
Change in deposits, net			280,154	488,609
Change in repurchase agreements and federal funds purchased, net			(63,840)	135,365
Proceeds from Federal Home Loan Bank advances			0	25,000
Payments on advances from Federal Home Loan Bank			(15)	(25,015)
Payment of finance lease liabilities			(14)	(10)
Issuance of common stock			719	689
Repurchase of common stock			0	(1,099)
Dividends paid			(20,798)	(20,308)
Net cash provided by financing activities			196,206	603,231
Net decrease in cash and cash equivalents			(130,459)	(6,915)
Cash and cash equivalents at beginning of period			338,235	264,683	264,683
Cash and cash equivalents at end of period	$ 207,776	$ 257,768	207,776	257,768	$ 338,235
Supplemental disclosures:
Income taxes paid			16,885	13,100
Interest paid			10,948	18,567
Non-cash activities:
Loans to facilitate the sale of other real estate owned and repossessed assets			1,095	2,279
Common stock dividends accrued, paid in subsequent quarter			247	236
Real estate acquired in settlement of loans			$ 929	$ 2,100