Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Unrecognized Tax Benefits	$ 13,009	$ 13,162	$ 15,990	$ 11,401
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	3,000	$ 1,200
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 3,500