Short-Term Borrowings - Components of short-term borrowings (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Total short-term borrowings	$ 635	$ 10,611
Average balance during the year	$ 734	$ 3,886
Weighted-average annual interest rate during the year	0.25%	0.59%
Maximum month-end balance	$ 887	$ 10,611
Federal Funds Purchased
Short-term Debt [Line Items]
Total short-term borrowings	0	10,000
Securities Sold under Agreements to Repurchase
Short-term Debt [Line Items]
Total short-term borrowings	$ 635	$ 611