Loans and reserve for credit losses (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Commercial real estate:
Total loans, gross		$ 2,104,412	$ 1,687,929
Acceptable
Commercial real estate:
Total loans, gross		2,018,583	1,571,542
Pass-Watch
Commercial real estate:
Total loans, gross		31,954	36,052
Special Mention
Commercial real estate:
Total loans, gross		20,559	40,836
Substandard
Commercial real estate:
Total loans, gross		33,316	39,499
Originated Loans
Commercial real estate:
Total loans, gross	[1]	1,819,334	1,452,978
Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	1,760,349	1,376,860
Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	22,713	29,668
Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	10,934	20,648
Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	25,338	25,802
Acquired Loans
Commercial real estate:
Total loans, gross	[2]	285,078	234,951
Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	258,234	194,682
Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	9,241	6,384
Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	9,625	20,188
Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	7,978	13,697
Commercial real estate portfolio | Commercial real estate loans
Commercial real estate:
Total loans, gross		1,003,608	834,893
Commercial real estate portfolio | Commercial real estate loans | Acceptable
Commercial real estate:
Total loans, gross		956,746	759,665
Commercial real estate portfolio | Commercial real estate loans | Pass-Watch
Commercial real estate:
Total loans, gross		18,430	24,679
Commercial real estate portfolio | Commercial real estate loans | Special Mention
Commercial real estate:
Total loans, gross		15,107	22,675
Commercial real estate portfolio | Commercial real estate loans | Substandard
Commercial real estate:
Total loans, gross		13,325	27,874
Commercial real estate portfolio | Commercial real estate loans | Originated Loans
Commercial real estate:
Total loans, gross	[1]	813,084	694,474
Commercial real estate portfolio | Commercial real estate loans | Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	789,384	654,250
Commercial real estate portfolio | Commercial real estate loans | Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	11,241	18,448
Commercial real estate portfolio | Commercial real estate loans | Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	5,482	5,948
Commercial real estate portfolio | Commercial real estate loans | Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	6,977	15,828
Commercial real estate portfolio | Commercial real estate loans | Acquired Loans
Commercial real estate:
Total loans, gross	[2]	190,524	140,419
Commercial real estate portfolio | Commercial real estate loans | Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	167,362	105,415
Commercial real estate portfolio | Commercial real estate loans | Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	7,189	6,231
Commercial real estate portfolio | Commercial real estate loans | Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	9,625	16,727
Commercial real estate portfolio | Commercial real estate loans | Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	6,348	12,046
Commercial real estate portfolio | Owner occupied
Commercial real estate:
Total loans, gross		391,211	308,331
Commercial real estate portfolio | Owner occupied | Acceptable
Commercial real estate:
Total loans, gross		368,306	277,194
Commercial real estate portfolio | Owner occupied | Pass-Watch
Commercial real estate:
Total loans, gross		12,229	12,103
Commercial real estate portfolio | Owner occupied | Special Mention
Commercial real estate:
Total loans, gross		2,965	8,767
Commercial real estate portfolio | Owner occupied | Substandard
Commercial real estate:
Total loans, gross		7,711	10,267
Commercial real estate portfolio | Owner occupied | Originated Loans
Commercial real estate:
Total loans, gross	[1]	298,721	263,095
Commercial real estate portfolio | Owner occupied | Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	282,438	243,113
Commercial real estate portfolio | Owner occupied | Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	9,007	8,623
Commercial real estate portfolio | Owner occupied | Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	1,302	1,426
Commercial real estate portfolio | Owner occupied | Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	5,974	9,933
Commercial real estate portfolio | Owner occupied | Acquired Loans
Commercial real estate:
Total loans, gross	[2]	92,490	45,236
Commercial real estate portfolio | Owner occupied | Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	85,868	34,081
Commercial real estate portfolio | Owner occupied | Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	3,222	3,480
Commercial real estate portfolio | Owner occupied | Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	1,663	7,341
Commercial real estate portfolio | Owner occupied | Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	1,737	334
Commercial real estate portfolio | Non-owner occupied
Commercial real estate:
Total loans, gross		612,397	526,562
Commercial real estate portfolio | Non-owner occupied | Acceptable
Commercial real estate:
Total loans, gross		588,440	482,471
Commercial real estate portfolio | Non-owner occupied | Pass-Watch
Commercial real estate:
Total loans, gross		6,201	12,576
Commercial real estate portfolio | Non-owner occupied | Special Mention
Commercial real estate:
Total loans, gross		12,142	13,908
Commercial real estate portfolio | Non-owner occupied | Substandard
Commercial real estate:
Total loans, gross		5,614	17,607
Commercial real estate portfolio | Non-owner occupied | Originated Loans
Commercial real estate:
Total loans, gross	[1]	514,363	431,379
Commercial real estate portfolio | Non-owner occupied | Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	506,946	411,137
Commercial real estate portfolio | Non-owner occupied | Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	2,234	9,825
Commercial real estate portfolio | Non-owner occupied | Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	4,180	4,522
Commercial real estate portfolio | Non-owner occupied | Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	1,003	5,895
Commercial real estate portfolio | Non-owner occupied | Acquired Loans
Commercial real estate:
Total loans, gross	[2]	98,034	95,183
Commercial real estate portfolio | Non-owner occupied | Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	81,494	71,334
Commercial real estate portfolio | Non-owner occupied | Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	3,967	2,751
Commercial real estate portfolio | Non-owner occupied | Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	7,962	9,386
Commercial real estate portfolio | Non-owner occupied | Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	4,611	11,712
Construction portfolio | Construction
Commercial real estate:
Total loans, gross		211,038	130,352
Construction portfolio | Construction | Acceptable
Commercial real estate:
Total loans, gross		210,609	129,349
Construction portfolio | Construction | Pass-Watch
Commercial real estate:
Total loans, gross		0	0
Construction portfolio | Construction | Special Mention
Commercial real estate:
Total loans, gross		0	971
Construction portfolio | Construction | Substandard
Commercial real estate:
Total loans, gross		429	32
Construction portfolio | Construction | Originated Loans
Commercial real estate:
Total loans, gross	[1]	200,654	119,723
Construction portfolio | Construction | Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	200,278	118,752
Construction portfolio | Construction | Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	0	0
Construction portfolio | Construction | Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	0	971
Construction portfolio | Construction | Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	376	0
Construction portfolio | Construction | Acquired Loans
Commercial real estate:
Total loans, gross	[2]	10,384	10,629
Construction portfolio | Construction | Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	10,331	10,597
Construction portfolio | Construction | Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	0	0
Construction portfolio | Construction | Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	0	0
Construction portfolio | Construction | Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	53	32
Residential real estate portfolio | Residential real estate
Commercial real estate:
Total loans, gross		431,842	298,390
Residential real estate portfolio | Residential real estate | Acceptable
Commercial real estate:
Total loans, gross		428,202	296,725
Residential real estate portfolio | Residential real estate | Pass-Watch
Commercial real estate:
Total loans, gross		1,988	0
Residential real estate portfolio | Residential real estate | Special Mention
Commercial real estate:
Total loans, gross		0	0
Residential real estate portfolio | Residential real estate | Substandard
Commercial real estate:
Total loans, gross		1,652	1,665
Residential real estate portfolio | Residential real estate | Originated Loans
Commercial real estate:
Total loans, gross	[1]	377,374	237,084
Residential real estate portfolio | Residential real estate | Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	376,713	236,574
Residential real estate portfolio | Residential real estate | Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	0	0
Residential real estate portfolio | Residential real estate | Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	0	0
Residential real estate portfolio | Residential real estate | Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	661	510
Residential real estate portfolio | Residential real estate | Acquired Loans
Commercial real estate:
Total loans, gross	[2]	54,468	61,306
Residential real estate portfolio | Residential real estate | Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	51,489	60,151
Residential real estate portfolio | Residential real estate | Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	1,988	0
Residential real estate portfolio | Residential real estate | Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	0	0
Residential real estate portfolio | Residential real estate | Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	991	1,155
Commercial and industrial portfolio | Commercial and industrial
Commercial real estate:
Total loans, gross		414,436	384,444
Commercial and industrial portfolio | Commercial and industrial | Acceptable
Commercial real estate:
Total loans, gross		379,550	345,968
Commercial and industrial portfolio | Commercial and industrial | Pass-Watch
Commercial real estate:
Total loans, gross		11,536	11,373
Commercial and industrial portfolio | Commercial and industrial | Special Mention
Commercial real estate:
Total loans, gross		5,452	17,190
Commercial and industrial portfolio | Commercial and industrial | Substandard
Commercial real estate:
Total loans, gross		17,898	9,913
Commercial and industrial portfolio | Commercial and industrial | Originated Loans
Commercial real estate:
Total loans, gross	[1]	386,150	363,335
Commercial and industrial portfolio | Commercial and industrial | Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	351,914	328,934
Commercial and industrial portfolio | Commercial and industrial | Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	11,472	11,220
Commercial and industrial portfolio | Commercial and industrial | Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	5,452	13,729
Commercial and industrial portfolio | Commercial and industrial | Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	17,312	9,452
Commercial and industrial portfolio | Commercial and industrial | Acquired Loans
Commercial real estate:
Total loans, gross	[2]	28,286	21,109
Commercial and industrial portfolio | Commercial and industrial | Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	27,636	17,034
Commercial and industrial portfolio | Commercial and industrial | Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	64	153
Commercial and industrial portfolio | Commercial and industrial | Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	0	3,461
Commercial and industrial portfolio | Commercial and industrial | Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	586	461
Consumer portfolio | Consumer
Commercial real estate:
Total loans, gross		43,488	39,850
Consumer portfolio | Consumer | Acceptable
Commercial real estate:
Total loans, gross		43,476	39,835
Consumer portfolio | Consumer | Pass-Watch
Commercial real estate:
Total loans, gross		0	0
Consumer portfolio | Consumer | Special Mention
Commercial real estate:
Total loans, gross		0	0
Consumer portfolio | Consumer | Substandard
Commercial real estate:
Total loans, gross		12	15
Consumer portfolio | Consumer | Originated Loans
Commercial real estate:
Total loans, gross	[1]	42,072	38,362
Consumer portfolio | Consumer | Originated Loans | Acceptable
Commercial real estate:
Total loans, gross	[1]	42,060	38,350
Consumer portfolio | Consumer | Originated Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[1]	0	0
Consumer portfolio | Consumer | Originated Loans | Special Mention
Commercial real estate:
Total loans, gross	[1]	0	0
Consumer portfolio | Consumer | Originated Loans | Substandard
Commercial real estate:
Total loans, gross	[1]	12	12
Consumer portfolio | Consumer | Acquired Loans
Commercial real estate:
Total loans, gross	[2]	1,416	1,488
Consumer portfolio | Consumer | Acquired Loans | Acceptable
Commercial real estate:
Total loans, gross	[2]	1,416	1,485
Consumer portfolio | Consumer | Acquired Loans | Pass-Watch
Commercial real estate:
Total loans, gross	[2]	0	0
Consumer portfolio | Consumer | Acquired Loans | Special Mention
Commercial real estate:
Total loans, gross	[2]	0	0
Consumer portfolio | Consumer | Acquired Loans | Substandard
Commercial real estate:
Total loans, gross	[2]	$ 0	$ 3

[1] Loans organically made through the Company’s normal and customary origination process, including ARM purchases.

[2] Loans acquired in the Home merger and PPFS merger.