Short-Term Borrowings - Balance, Weighted Average and Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Balance	$ 488,383	$ 590,161	$ 710,832
Weighted Average Interest Rate	2.57%	1.38%	0.70%
Interest Expense	$ 11,304	$ 7,453	$ 2,718
REPOs
Short-term Debt [Line Items]
Balance	$ 18,383	$ 50,161	$ 50,832
Weighted Average Interest Rate	0.46%	0.39%	0.01%
Interest Expense	$ 222	$ 54	$ 5
FHLB advances
Short-term Debt [Line Items]
Balance	$ 470,000	$ 540,000	$ 660,000
Weighted Average Interest Rate	2.65%	1.47%	0.76%
Interest Expense	$ 11,082	$ 7,399	$ 2,713