Parent Company Only Financial Information (Statement of Cash Flow) (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	Dec. 31, 2017
Operating activities:
Net income	$ 20,573	$ 10,210	$ 4,749	$ (765)	$ 14,860	$ 14,868	$ 9,598	$ 14,369	$ 34,767	$ 53,695	$ 46,255
Depreciation, amortization and accretion, net									25,639	17,861	18,204
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on investment securities	751	$ (2)	$ (62)	(319)	(94)	$ (97)	$ 57	(30)	368	(164)	146
Net cash provided by operating activities									85,483	67,157	75,243
Investing activities:
Business acquisitions, net of cash received									(94,856)	7,814	4,695
Financing activities:
Payments on long-term borrowings									(2,715)	(3,501)	(4,591)
Proceeds from issuance of common shares									594	6	25
Cash dividends paid									(27,052)	(25,942)	(20,915)
Net cash provided by (used in) financing activities									345,343	(30,629)	60,331
Net increase in cash, cash equivalents and restricted cash									36,907	37,581	5,418
Cash, cash equivalents and restricted cash at beginning of period				115,193				77,612	115,193	77,612	72,194
Cash, cash equivalents, and restricted cash at end of period	152,100				115,193				152,100	115,193	77,612
Supplemental cash flow information:
Payments for Repurchase of Common Stock									29,281	805	0
Holding Company
Operating activities:
Net income									34,767	53,695	46,255
Depreciation, amortization and accretion, net									161	168	9,177
Adjustments to reconcile net income to net cash provided by operating activities:
Excess dividends from (equity in) undistributed earnings of subsidiaries									8,259	(22,517)	(34,115)
Gain on investment securities									(8)	0	0
Other, net									8,492	3,801	31
Net cash provided by operating activities									51,671	35,147	21,348
Investing activities:
Proceeds from Sale, Maturity and Collection of Investments									10	0	5,388
Investment in subsidiaries									(35,238)	(18,874)	(31,813)
Decrease in receivable from subsidiary									34,719	18,869	32,236
Business acquisitions, net of cash received									0	(1,438)	(637)
Payments for (Proceeds from) Other Investing Activities									(76)	226	228
Net cash (used in) provided by investing activities									(585)	(1,217)	5,402
Financing activities:
Purchase of treasury stock										(1,650)	(1,380)
Proceeds from issuance of common shares									594	6	25
Cash dividends paid									(27,052)	(25,942)	(20,915)
Net cash provided by (used in) financing activities									(56,867)	(27,586)	(22,270)
Net increase in cash, cash equivalents and restricted cash									(5,781)	6,344	4,480
Cash and cash equivalents at the beginning of year					20,144					20,144	13,800	$ 9,320
Cash, cash equivalents and restricted cash at beginning of period				$ 20,144				$ 13,800	20,144	13,800
Cash, cash equivalents, and restricted cash at end of period	$ 14,363				$ 20,144				14,363	20,144	13,800
Supplemental cash flow information:
Interest paid									385	$ 544	$ 513
Payments for Repurchase of Common Stock									$ (30,409)