Investment Securities - Schedule of Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Investment income, net	$ 84	$ 901
Cash and cash equivalents
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Investment income, net		89
Short-term investments
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Investment income, net	37	452
Investment securities
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Investment income, net	$ 47	$ 360