Loans - (Impaired Loans - Average Recorded Investment and Interest Income Recognized) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	$ 27,445	$ 16,324	$ 26,908
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	387	363	598
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	21,716	20,326	11,739
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	382	252	265
Impaired Financing Receivable, Average Recorded Investment	49,161	36,650	38,647
Impaired Financing Receivable, Interest Income, Cash Basis Method	769	615	863
Commercial and Industrial [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	7,909	5,049	21,827
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	252	266	414
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	3,545	6,273	893
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	198	1	7
Owner-Occupied [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,249	2,221	1,018
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	92	83	51
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	703	1,230	1,166
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	20	27	40
Agriculture [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,830	1,961	3,458
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method			126
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	162	276	158
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	5	4
Energy Loans [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	12,565	5,679
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	10,008	3,092
Commercial Loan [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	25,553	14,910	26,303
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	344	349	591
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	14,418	10,871	2,217
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	223	32	47
Commercial Construction [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		188
Multifamily [Member]
Loans [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	34	60
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	2	1
Non Owner-Occupied [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	368	157
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	22
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	268	1,667	1,095
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	13	48	56
Total Commercial Real Estate [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	368	345
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	22
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	302	1,727	1,095
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	15	49	56
Senior lien
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,466	956	605
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	19	15	7
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	5,200	5,911	6,594
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	88	119	101
Junior lien
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	54	113
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	2
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,600	1,725	1,568
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	56	51	60
Residential Real Estate Segment [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,520	1,069	605
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	21	15	7
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	6,800	7,636	8,162
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	144	170	161
Consumer [Member]
Loans [Line Items]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	4
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	$ 196	92	265
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method		$ 1	$ 1