Industry Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fee revenue and other income:
Income from customers									$ 86,136	$ 83,368	$ 79,907
Intersegment income (expense)
Net interest income (expense) after provision for loan losses:
Income from customers									39,401	37,449	37,299
Intersegment income (expense)
Depreciation and amortization									3,653	3,416	3,096
Income taxes	$ 1,806	$ 1,855	$ 2,035	$ 2,020	$ 2,017	$ 2,083	$ 1,932	$ 1,946	7,716	7,978	7,759
Net income	6,424	$ 6,222	$ 5,869	$ 5,833	6,089	$ 5,880	$ 5,548	$ 5,539	24,348	23,056	24,033
Goodwill	11,590				11,590				11,590	11,590	11,590
Other intangible assets, net	1,997				2,405				1,997	2,405	2,762
Total assets	1,504,839				1,455,506				1,504,839	1,455,506	1,500,731
Information Services [Member]
Fee revenue and other income:
Income from customers									84,612	82,144	78,773
Intersegment income (expense)									12,164	10,078	9,210
Net interest income (expense) after provision for loan losses:
Income from customers									13,820	14,598	15,678
Intersegment income (expense)									2	12	12
Depreciation and amortization									3,368	3,164	2,795
Income taxes									1,478	2,818	3,006
Net income									14,049	14,635	16,379
Goodwill	11,454				11,454				11,454	11,454	11,454
Other intangible assets, net	1,997				2,405				1,997	2,405	2,762
Total assets	763,999				702,491				763,999	702,491	782,844
Banking Services [Member]
Fee revenue and other income:
Income from customers									1,524	1,224	1,134
Intersegment income (expense)									1,575	1,648	1,504
Net interest income (expense) after provision for loan losses:
Income from customers									25,581	22,851	21,621
Intersegment income (expense)									(2)	(12)	(12)
Depreciation and amortization									165	151	182
Income taxes									6,238	5,160	4,753
Net income									10,299	8,421	7,654
Goodwill	136				136				136	136	136
Other intangible assets, net
Total assets	756,164				761,739				756,164	761,739	755,400
Corporate Eliminations and Other [Member]
Fee revenue and other income:
Income from customers
Intersegment income (expense)									(13,739)	(11,726)	(10,714)
Net interest income (expense) after provision for loan losses:
Income from customers
Intersegment income (expense)
Depreciation and amortization									120	101	119
Income taxes
Net income
Goodwill
Other intangible assets, net
Total assets	$ (15,324)				$ (8,724)				$ (15,324)	$ (8,724)	$ (37,513)