Cash, Cash Equivalents and Available for Sale Securities - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) for Unrealized Loss on Available for Sale Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	$ 117,203	$ 123,959	$ 38,041
Other comprehensive income	3	0	0
Ending balance	191,563	117,203	123,959
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent
Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	0	0
Current period changes in fair value before reclassifications, net of tax	3	0
Amounts reclassified from accumulated other comprehensive income, net of tax	0	0
Other comprehensive income	3	0
Ending balance	$ 3	$ 0	$ 0