Borrowings (Short-term borrowings) (Details 1) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Short-term Borrowings
Securities Sold Under Agreements to Repurchase	$ 604,306	$ 504,296
Amounts Outstanding	0	199
Securities Sold Under Agreements to Repurchase
Short-term Borrowings
Amounts Outstanding	$ 2,200	$ 4,196
Weighted Average Interest Rate (as a percent)	1.87%	1.19%
Long-term Repurchase Agreements with Government Entities
Short-term Borrowings
Securities Sold Under Agreements to Repurchase	$ 2,100	$ 100
Long-term Repurchase Agreements with Private Institutions
Short-term Borrowings
Securities Sold Under Agreements to Repurchase	$ 600,000	$ 500,000