Borrowed Funds and Mandatorily Redeemable Securities (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Short-term borrowings:
Short-term borrowings	$ 214,595	$ 291,943
Short-term borrowings, weighted average interest rate	0.57%	0.34%
Federal funds purchased
Short-term borrowings:
Short-term borrowings	$ 56,000	$ 0
Short-term borrowings, weighted average interest rate	1.63%	0.00%
Security repurchase agreements
Short-term borrowings:
Short-term borrowings	$ 149,834	$ 162,913
Short-term borrowings, weighted average interest rate	0.20%	0.17%
Commercial paper
Short-term borrowings:
Short-term borrowings	$ 6,115	$ 5,761
Short-term borrowings, weighted average interest rate	0.27%	0.27%
Other short-term borrowings
Short-term borrowings:
Short-term borrowings	$ 2,646	$ 123,269
Short-term borrowings, weighted average interest rate	0.00%	0.57%