Long-Term Borrowings - Components (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Long-term borrowings
Long-term borrowings	$ 400,026	$ 34
Remaining borrowing capacity	1,700,000
Capital lease
Long-term borrowings
Long-term borrowings	$ 26	$ 34
Interest rate (as a percent)	6.78%
FHLB advance
Long-term borrowings
Long-term borrowings	$ 400,000
Interest rate (as a percent)	2.84%