Parent Company Financial Statements (Statement of Income) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income:
Total income	[1]									$ 200,494	$ 194,404	$ 184,340
Expenses:
Interest on junior subordinated debentures										980	869	613
Legal and professional fees										2,535	2,427	2,294
Change in fair value of contingent consideration										0	(187)	(643)
Income before income taxes		$ 19,857	$ 24,050	$ 21,935	$ 22,337	$ 21,559	$ 22,252	$ 22,416	$ 20,465	88,179	86,692	77,640
Income tax benefit		(4,321)	(5,236)	(4,662)	(4,842)	(4,523)	(4,741)	(4,742)	(4,254)	(19,061)	(18,260)	(31,715)
Net income		$ 15,536	$ 18,814	$ 17,273	$ 17,495	$ 17,036	$ 17,511	$ 17,674	$ 16,211	69,118	68,432	45,925
Parent Company [Member]
Income:
Total income										36,823	32,418	27,918
Expenses:
Interest on junior subordinated debentures										980	869	613
Legal and professional fees										147	187	169
Change in fair value of contingent consideration										0	(187)	(643)
Other										337	324	298
Total expenses										1,464	1,193	437
Income before income taxes										35,359	31,225	27,481
Income tax benefit										301	284	340
Income before equity in undistributed earnings (losses) of subsidiaries										35,660	31,509	27,821
Net income										69,118	68,432	45,925
Bank [Member]
Income:
Dividends from subsidiaries										36,796	32,394	27,900
Expenses:
Equity in undistributed earnings (losses) of subsidiaries										33,445	36,876	18,193
Non-bank [Member]
Income:
Dividends from subsidiaries										27	24	18
Expenses:
Equity in undistributed earnings (losses) of subsidiaries										$ 13	$ 47	$ (89)

[1] As reported in the Consolidated Statements of Income.