Loans - Other (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Loans and Leases Receivable, Other Information [Abstract]
Net deferred loan origination fees and unamortized premium and discount	$ 17,000	$ 19,800
Non-accretable discount on acquired credit impaired loans	13,000	13,400
Accrued interest receivable on loans	7,200	7,300
Consumer and other [Member]
Loans and Leases Receivable, Other Information [Abstract]
Deposit Liabilities Reclassified as Loans Receivable	69	$ 560
Loans	$ 2
Reserved Based Energy Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Percentage of total funded loans	3.20%	4.20%
Loans	$ 46,200	$ 32,300
Energy Related Service Industry Loans [Member]
Loans and Leases Receivable, Other Information [Abstract]
Percentage of total funded loans	4.30%	5.20%
Loans	$ 9,300	$ 291