Taxes - Changes in the Reserve for Income Taxes, Excluding Interest and Penalties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance of reserve for income taxes	$ 7,294	$ 6,749
Gross amounts of increases in unrecognized tax benefits as a result of tax positions taken in prior periods		69
Gross amounts of increases in unrecognized tax benefits as a result of tax positions taken in prior periods	199
Gross amounts of increases in unrecognized tax benefits as a result of tax positions taken in the current period	5,259	1,499
Gross amounts of decreases in unrecognized tax benefits as a result of the expiration of the applicable statutes of limitations	(1,161)	(1,023)
Balance of reserve for income taxes	$ 11,591	$ 7,294