Income Taxes - Components of Income Tax Expense (Benefit) - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
Federal	$ 0	$ 0	$ 0
State	0	0	0
Total current income tax expense	0	0	0
Deferred
Federal	4,514	2,693	1,939
State	16	20	4
Total deferred income tax expense	4,530	2,713	1,943
Total income tax expense	$ 4,530	$ 2,713	$ 1,943