Investment Securities - Carrying value of other investment securities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Other investment securities
Carrying Value	$ 133,430	$ 49,124	$ 49,124
Other-than-temporary impairment on securities	0
Federal Home Loan Bank stock
Other investment securities
Carrying Value	44,754	43,044	43,044
Federal Reserve Bank Stock
Other investment securities
Carrying Value	78,194
Investment in unconsolidated subsidiaries
Other investment securities
Carrying Value	4,941	3,563	3,563
Other nonmarketable investment securities
Other investment securities
Carrying Value	$ 5,541	$ 2,517	$ 2,517