Parent Company Financial Statements (Statements of Income) (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	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Dividend income from subsidiary										$ 1,315	$ 1,135	$ 1,005
Interest on borrowings										7,456	5,585	4,506
Income before income tax expense	$ 17,479	$ 17,295	$ 15,104	$ 15,899	$ 16,162		$ 16,817	$ 14,955	$ 14,420	65,777	62,354	57,539
Income tax benefit (expense)	(3,502)	(3,238)	(2,887)	(3,079)	(19,335)		(5,478)	(4,721)	(4,344)	(12,706)	(33,878)	(17,472)
Net income	$ 13,977	$ 14,057	$ 12,217	$ 12,820	$ (3,173)		$ 11,339	$ 10,234	$ 10,076	53,071	28,476	40,067
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Dividend income from subsidiary										28,100	16,800	16,000
Other income										283	145	239
Total operating income										28,383	16,945	16,239
Interest on borrowings										3,415	3,408	3,415
Fees to Bank										160	160	160
Other operating expenses										569	592	748
Total operating expenses										4,144	4,160	4,323
Income before equity in undistributed income of subsidiaries and income taxes										24,239	12,785	11,916
Equity in undistributed income of subsidiaries										27,971	17,405	26,773
Income before income tax expense										52,210	30,190	38,689
Income tax benefit (expense)										861	(1,714)	1,378
Net income										$ 53,071	$ 28,476	$ 40,067

[1] (1) In the fourth quarter of 2017, the Company recognized $14.3 million of additional income tax expense upon the revaluation of its deferred tax assets and liabilities upon enactment of the Tax Act on December 22, 2017, which lowered the federal corporate tax rate from 35.0% to 21.0%, effective January 1, 2018. The impact to fourth quarter 2017 basic and diluted EPS was $0.91 per share.