Loans - Other (Details 2) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Loans and Leases Receivable, Other Information [Abstract]
Net deferred loan origination fees and unamortized premium and discount	$ 9,700	$ 10,300
Non-accretable discount on acquired credit impaired loans	582	1,400
Accrued interest receivable on loans	4,900	4,500
Consumer and other [Member]
Loans and Leases Receivable, Other Information [Abstract]
Deposit Liabilities Reclassified as Loans Receivable	$ 35	51
Loans		$ 95
Reserved Based Energy Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Percentage of total funded loans	6.80%	8.70%
Loans	$ 18,300
Energy Related Service Industry Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Percentage of total funded loans	3.90%	5.20%
Loans	$ 400