Long-Term Borrowings - Components (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Long-term borrowings
Finance lease liabilities	$ 28	$ 26
Long-term borrowings	$ 400,028	$ 600,026
Finance lease obligation, annual interest rate	6.78%	6.78%
FHLB fixed-rate advance
Long-term borrowings
Long-term borrowings	$ 400,000	$ 600,000
Remaining borrowing capacity	$ 1,600,000	$ 1,300,000
Weighted average interest rate	2.80%	2.80%