Goodwill and other intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-lived Intangible Assets [Roll Forward]
Core deposit intangible, net, beginning of period	$ 7,683
Total core deposit intangible, end of period	6,863	$ 7,683
Other Goodwill Disclosures
Goodwill	78,610	80,082
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Gross core deposit intangibles balance, beginning of period		8,196	$ 529
Accumulated amortization, beginning of period		(513)	0
Finite-lived Intangible Assets [Roll Forward]
Core deposit intangible, net, beginning of period	7,683	529
Established through acquisitions	0	7,667
CDI current period amortization	(820)	(513)	0
Total core deposit intangible, end of period	$ 6,863	7,683	$ 529
Other Goodwill Disclosures
Core deposit intangible, useful life	10 years
Home Federal Bancorp. Inc.
Other Goodwill Disclosures
Goodwill		$ 78,600