Securities Equity Securities - unrealized gains and losses (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Gains recognized during the period on equity securities	$ 0		$ 0	$ 16,425	$ 0
Less: Gains recognized during the period on equity securities sold during the period	0		0	(3,000)	0
Unrealized gains recognized during the reporting period on equity securities still held at the reporting date	$ 0		0	$ 13,425	0
Visa Class B shares, shares sold		17,360
Visa Class B shares, gain on sale		$ 3,000
Visa Class B shares, remaining shares	77,683			77,683
Equity Securities	$ 13,425	$ 13,425	$ 0	$ 13,425	$ 0	$ 0	$ 0	$ 0