Parent Company Financial Statements, Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities [Abstract]
Net income	$ 87,939	$ 59,504	$ 64,540
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Depreciation	5,033	5,346	5,515
Deferred taxes	2,330	(2,909)	(1,412)
Stock-based compensation	850	944	859
Gain on debt repurchase	0	0	(219)
Changes in [Abstract]
Other assets	4,918	1,845	4,941
Other liabilities	(2,387)	4,147	(2,440)
Net cash provided by operating activities	115,695	62,379	83,458
Cash flows from investing activities [Abstract]
Net sales (purchases) of premises and equipment	(2,373)	(1,482)	(2,570)
Net cash used in investing activities	(358,620)	(693,526)	(34,491)
Cash flows from financing activities [Abstract]
Issuance of common stock	965	926	1,264
Repurchase of common stock	0	(1,099)	0
Dividends paid	(27,916)	(27,142)	(26,235)
Net cash provided by financing activities	216,446	704,699	74,266
Cash and cash equivalents at beginning of year	338,235
Cash and cash equivalents at end of year	311,756	338,235
Parent Company [Member]
Cash flows from operating activities [Abstract]
Net income	87,939	59,504	64,540
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Depreciation	69	112	144
Equity in undistributed earnings of subsidiaries	(59,476)	(33,792)	(34,621)
Deferred taxes	3,759	451	(4,907)
Stock-based compensation	850	944	859
Gain on debt repurchase	0	0	(219)
Changes in [Abstract]
Other assets	(5,403)	(115)	1
Other liabilities	1,037	(318)	683
Net cash provided by operating activities	28,775	26,786	26,480
Cash flows from investing activities [Abstract]
Payment for investment in subsidiary	0	0	(1,281)
Net sales (purchases) of premises and equipment	(66)	(55)	(78)
Net cash used in investing activities	(66)	(55)	(1,359)
Cash flows from financing activities [Abstract]
Issuance of common stock	965	926	1,264
Repurchase of common stock	0	(1,099)	0
Dividends paid	(27,916)	(27,142)	(26,235)
Net cash provided by financing activities	(26,951)	(27,315)	(24,971)
Net increase (decrease) in cash and cash equivalents	1,758	(584)	150
Cash and cash equivalents at beginning of year	1,505	2,089	1,939
Cash and cash equivalents at end of year	$ 3,263	$ 1,505	$ 2,089