Short-Term Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Short-term borrowings
Total short-term borrowings	$ 422,279	$ 32,403
Securities sold under agreements to repurchase
Short-term borrowings
Total short-term borrowings	22,279	6,103
Overnight borrowings
Short-term borrowings
Total short-term borrowings	$ 400,000	$ 26,300