Income Taxes - Unrecognized Tax Benefits (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)
Income Taxes
Unrecognized tax benefits at the beginning of year	$ 14,553,000
Gross increases - prior year tax positions	67,000
Unrecognized tax benefits at end of year	14,620,000
Interest and penalties in year-end balance	67,000
Interest expense related to uncertain tax positions	$ 67,000