Parent Company Financial Statements (Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Net income	$ 18,278	$ 16,775	$ 10,940	$ 13,493	$ 15,238	$ 14,488	$ 13,204	$ 14,273	$ 59,486	$ 57,203	$ 53,071
Increase in other assets									(10,912)	(1,005)	(9,029)
Net cash provided by operating activities									18,230	32,871	64,334
Investing Activities
Net cash used in investing activities									(294,452)	(55,835)	(276,777)
Financing Activities
Common stock repurchases									(9,689)	(20,795)	(27)
Cash dividends paid on common stock									(19,842)	(18,572)	(17,170)
Net cash provided by financing activities									346,360	31,601	176,471
Net increase (decrease) in cash, cash equivalents and restricted cash									70,138	8,637	(35,972)
Cash, cash equivalents and restricted cash at beginning of year				75,636				66,999	75,636	66,999	102,971
Cash, cash equivalents and restricted cash at end of year	145,774				75,636				145,774	75,636	66,999
Parent Company [Member]
Operating Activities
Net income									59,486	57,203	53,071
Equity in undistributed income of subsidiaries									(23,299)	(22,579)	(27,971)
Increase in other assets									(5,228)	(2,935)	(1,772)
Increase (decrease) in due to subsidiaries									71	(109)	82
(Decrease) increase in other liabilities									(83)	4,298	(4,763)
Net cash provided by operating activities									30,947	35,878	18,647
Investing Activities
Proceeds from Sale of Available-for-sale Securities, Equity									1,712	0	214
Net cash used in investing activities									1,712	0	214
Financing Activities
Net proceeds from issuance of common stock									1,670	1,683	1,338
Common stock repurchases									(9,689)	(20,795)	(27)
Cash dividends paid on common stock									(19,842)	(18,572)	(17,170)
Net cash provided by financing activities									(27,861)	(37,684)	(15,859)
Net increase (decrease) in cash, cash equivalents and restricted cash									4,798	(1,806)	3,002
Cash, cash equivalents and restricted cash at beginning of year				$ 30,561				$ 32,367	30,561	32,367	29,365
Cash, cash equivalents and restricted cash at end of year	$ 35,359				$ 30,561				$ 35,359	$ 30,561	$ 32,367