Investment Securities - Schedule of Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Separate Account Investment [Line Items]
Investment income, net	$ 179	$ 823	$ 340	$ 2,226
Cash and cash equivalents
Fair Value, Separate Account Investment [Line Items]
Investment income, net	0	1	0	108
Short-term investments
Fair Value, Separate Account Investment [Line Items]
Investment income, net	62	519	139	1,141
Investment securities
Fair Value, Separate Account Investment [Line Items]
Investment income, net	$ 117	$ 303	$ 201	$ 977