Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Operating Activities
Net income			$ 46,606	$ 47,995
Items not requiring (providing) cash
Provision for credit losses	$ 2,052	$ 376	17,709	1,636
Depreciation and amortization			7,539	7,064
Share based compensation			105	165
Mortgage servicing rights income			(630)	(1,679)
Mortgage servicing rights net impairment	1,500		4,673	59	$ 192
Premium amortization on securities, net			6,649	4,119
(Gain) loss on sale of investment securities	(1,088)	0	(1,675)	85
Gain on sale of mortgage loans	(8,813)	(2,702)	(18,906)	(6,089)
Proceeds from sales of loans			436,285	192,163
Loans originated for sale			(426,344)	(186,096)
Change in cash value life insurance			(1,677)	(1,624)
Gain on sale of other real estate owned			(119)	(115)
Net change in:
Interest receivable			(1,628)	(1,555)
Interest payable			(581)	(132)
Other assets			(7,048)	97,136
Other liabilities			1,873	11,413
Net cash provided by operating activities			62,831	164,545
Investing Activities
Purchases of securities available for sale			(396,133)	(301,426)
Proceeds from sales, maturities, calls and principal repayments of securities available for sale			237,645	200,067
Proceeds from maturities of securities held to maturity			26,359	6,990
Net change in interest-earning time deposits			(758)	7,289
Change in FHLB stock			(576)	(803)
Net change in loans			(394,167)	(87,905)
Proceeds on the sale of OREO and repossessed assets			1,426	2,935
Change in premises and equipment, net			(4,252)	(3,760)
Death benefit on bank owned life insurance			264	580
Repurchase of outstanding stock			(19,636)	(1,595)
Net cash used in investing activities			(549,828)	(48,883)
Net change in:
Deposits			405,287	35,237
Borrowings			37,654	(104,251)
Proceeds from issuance of stock			1,401	1,552
Net proceeds from issuance of subordinated notes			58,824	0
Dividends paid on common stock			(15,874)	(15,413)
Net cash provided by (used in) financing activities			487,292	(82,875)
Net Change in Cash and Cash Equivalents			295	32,787
Cash and Cash Equivalents, Beginning of Period			98,831	58,492	58,492
Cash and Cash Equivalents, End of Period	$ 99,126	$ 91,279	99,126	91,279	$ 98,831
Additional Supplemental Information
Interest paid			25,407	34,968
Income taxes paid			9,825	1,319
Transfer of loans to other real estate and repossessed assets			1,795	2,030
Transfer of premises to other real estate			0	1,705
Right-of-use assets exchanged for lease obligations			0	3,411
Salin
Investing Activities
Net cash received in acquisition, Salin			$ 0	$ 128,745