Parent Company Financial Statements (Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Payment of contingent consideration liability									$ (1,217)	$ 0	$ 0
Cash flows from operating activities:
Net income	$ 17,036	$ 17,511	$ 17,674	$ 16,211	$ 7,982	$ 12,962	$ 13,199	$ 11,782	68,432	45,925	46,481
Adjustments to reconcile net income to net cash provided by operating activities:
(Increase) decrease in other assets									(7,456)	(8,794)	984
Change in fair value of contingent consideration									(187)	(643)	(898)
Tax benefit from stock option exercises and other equity awards									496	508	1,016
Net cash provided by operating activities									82,876	59,385	59,749
Cash flows from investing activities:
Net cash used in investing activities									(481,831)	(179,706)	(625,377)
Cash flows from financing activities:
Proceeds from stock option exercises and issuance of other equity awards, net of awards surrendered									(671)	366	977
Cash dividends paid									(29,312)	(26,300)	(24,637)
Net cash provided by financing activities									409,507	95,447	575,794
Net increase (decrease) in cash and cash equivalents									10,552	(24,874)	10,166
Cash and cash equivalents at beginning of year				82,923		$ 82,923		107,797	82,923	107,797	97,631
Cash and cash equivalents at end of year	93,475				82,923		$ 82,923		93,475	82,923	107,797
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payment of contingent consideration liability									(1,217)	0	0
Cash flows from operating activities:
Net income									68,432	45,925	46,481
Adjustments to reconcile net income to net cash provided by operating activities:
Decrease (increase) in dividend receivable									8	(1,252)	(1,436)
(Increase) decrease in other assets									70	72	45
Increase (decrease) in accrued expenses and other liabilities									17	22	(12)
Change in fair value of contingent consideration									(187)	(643)	(898)
Tax benefit from stock option exercises and other equity awards									496	508	1,016
Other, net									(465)	(673)	(1,051)
Net cash provided by operating activities									31,448	25,855	22,233
Cash flows from financing activities:
Proceeds from stock option exercises and issuance of other equity awards, net of awards surrendered									(671)	366	978
Cash dividends paid									(29,312)	(26,300)	(24,637)
Net cash provided by financing activities									(31,200)	(25,934)	(23,659)
Net increase (decrease) in cash and cash equivalents									248	(79)	(1,426)
Cash and cash equivalents at beginning of year				$ 1,664				$ 1,743	1,664	1,743	3,169
Cash and cash equivalents at end of year	$ 1,912				$ 1,664				1,912	1,664	1,743
Bank [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Bank									(36,876)	(18,193)	(22,008)
Non-bank [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Bank									$ (47)	$ 89	$ 96