Summary of Significant Accounting Policies - Advertising Costs and Income Taxes (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Marketing and Advertising Expense [Abstract]
Advertising costs	$ 632,000	$ 303,000	$ 1,020,000	$ 789,000
Income Tax Disclosure [Abstract]
Uncertain tax positions	$ 0		$ 0		$ 0