Loans and reserve for credit losses (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Commercial real estate:
Owner occupied		$ 308,331	$ 259,109
Non-owner occupied		526,562	497,543
Total commercial real estate loans		834,893	756,652
Construction		130,352	125,428
Residential real estate		298,390	204,687
Commercial and industrial		384,444	368,475
Consumer		39,850	37,298
Total loans		1,687,929	1,492,540
Acceptable
Commercial real estate:
Owner occupied		277,194	220,545
Non-owner occupied		482,471	431,428
Total commercial real estate loans		759,665	651,973
Construction		129,349	117,936
Residential real estate		296,725	198,883
Commercial and industrial		345,968	331,045
Consumer		39,835	37,197
Total loans		1,571,542	1,337,034
Pass-Watch
Commercial real estate:
Owner occupied		12,103	9,874
Non-owner occupied		12,576	21,763
Total commercial real estate loans		24,679	31,637
Construction		0	5,418
Residential real estate		0	1,380
Commercial and industrial		11,373	18,872
Consumer		0	0
Total loans		36,052	57,307
Special Mention
Commercial real estate:
Owner occupied		8,767	9,435
Non-owner occupied		13,908	33,051
Total commercial real estate loans		22,675	42,486
Construction		971	1,850
Residential real estate		0	552
Commercial and industrial		17,190	14,676
Consumer		0	0
Total loans		40,836	59,564
Substandard
Commercial real estate:
Owner occupied		10,267	19,255
Non-owner occupied		17,607	11,301
Total commercial real estate loans		27,874	30,556
Construction		32	224
Residential real estate		1,665	3,872
Commercial and industrial		9,913	3,882
Consumer		15	101
Total loans		39,499	38,635
Originated Loans, Receivable
Commercial real estate:
Owner occupied	[1]	263,095	198,845
Non-owner occupied	[1]	431,379	383,287
Total commercial real estate loans	[1]	694,474	582,132
Construction	[1]	119,723	100,437
Residential real estate	[1]	237,084	122,478
Commercial and industrial	[1]	363,335	342,746
Consumer	[1]	38,362	34,897
Total loans	[1]	1,452,978	1,182,690
Originated Loans, Receivable | Acceptable
Commercial real estate:
Owner occupied	[1]	243,113	167,509
Non-owner occupied	[1]	411,137	350,420
Total commercial real estate loans	[1]	654,250	517,929
Construction	[1]	118,752	95,440
Residential real estate	[1]	236,574	119,280
Commercial and industrial	[1]	328,934	306,030
Consumer	[1]	38,350	34,852
Total loans	[1]	1,376,860	1,073,531
Originated Loans, Receivable | Pass-Watch
Commercial real estate:
Owner occupied	[1]	8,623	8,749
Non-owner occupied	[1]	9,825	10,383
Total commercial real estate loans	[1]	18,448	19,132
Construction	[1]	0	3,086
Residential real estate	[1]	0	1,380
Commercial and industrial	[1]	11,220	18,721
Consumer	[1]	0	0
Total loans	[1]	29,668	42,319
Originated Loans, Receivable | Special Mention
Commercial real estate:
Owner occupied	[1]	1,426	4,035
Non-owner occupied	[1]	4,522	16,145
Total commercial real estate loans	[1]	5,948	20,180
Construction	[1]	971	1,850
Residential real estate	[1]	0	552
Commercial and industrial	[1]	13,729	14,676
Consumer	[1]	0	0
Total loans	[1]	20,648	37,258
Originated Loans, Receivable | Substandard
Commercial real estate:
Owner occupied	[1]	9,933	18,552
Non-owner occupied	[1]	5,895	6,339
Total commercial real estate loans	[1]	15,828	24,891
Construction	[1]	0	61
Residential real estate	[1]	510	1,266
Commercial and industrial	[1]	9,452	3,319
Consumer	[1]	12	45
Total loans	[1]	25,802	29,582
Acquired Loans, Receivable
Commercial real estate:
Owner occupied	[2]	45,236	60,264
Non-owner occupied	[2]	95,183	114,256
Total commercial real estate loans	[2]	140,419	174,520
Construction	[2]	10,629	24,991
Residential real estate	[2]	61,306	82,209
Commercial and industrial	[2]	21,109	25,729
Consumer	[2]	1,488	2,401
Total loans	[2]	234,951	309,850
Acquired Loans, Receivable | Acceptable
Commercial real estate:
Owner occupied	[2]	34,081	53,036
Non-owner occupied	[2]	71,334	81,008
Total commercial real estate loans	[2]	105,415	134,044
Construction	[2]	10,597	22,496
Residential real estate	[2]	60,151	79,603
Commercial and industrial	[2]	17,034	25,015
Consumer	[2]	1,485	2,345
Total loans	[2]	194,682	263,503
Acquired Loans, Receivable | Pass-Watch
Commercial real estate:
Owner occupied	[2]	3,480	1,125
Non-owner occupied	[2]	2,751	11,380
Total commercial real estate loans	[2]	6,231	12,505
Construction	[2]	0	2,332
Residential real estate	[2]	0	0
Commercial and industrial	[2]	153	151
Consumer	[2]	0	0
Total loans	[2]	6,384	14,988
Acquired Loans, Receivable | Special Mention
Commercial real estate:
Owner occupied	[2]	7,341	5,400
Non-owner occupied	[2]	9,386	16,906
Total commercial real estate loans	[2]	16,727	22,306
Construction	[2]	0	0
Residential real estate	[2]	0	0
Commercial and industrial	[2]	3,461	0
Consumer	[2]	0	0
Total loans	[2]	20,188	22,306
Acquired Loans, Receivable | Substandard
Commercial real estate:
Owner occupied	[2]	334	703
Non-owner occupied	[2]	11,712	4,962
Total commercial real estate loans	[2]	12,046	5,665
Construction	[2]	32	163
Residential real estate	[2]	1,155	2,606
Commercial and industrial	[2]	461	563
Consumer	[2]	3	56
Total loans	[2]	13,697	$ 9,053
Acquired Covered Loans, Receivable
Commercial real estate:
Loans receivable net reported amount covered		$ 29,800

[1] Originated loans are loans organically made through the Company's normal and customary origination

[2] Acquired loans are loans acquired in the acquisition of Home, discussed elsewhere in this report, less acquired covered loans