Income Tax Uncertainties (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Income Tax Uncertainties
Unrecognized tax benefits, including penalties and interest that if recognized would impact effective tax rate	$ 2,600	$ 2,700
Unrecognized tax benefits, including penalties and interest, net of federal tax benefit that if recognized would affect effective tax rate	2,300	2,400
Total expense of interest and penalties, net of federal benefit related to uncertain tax positions	16
Accrued interest and penalties related to uncertain tax positions	600	700
Accrued interest and penalties related to uncertain tax positions, net of federal benefit	$ 500	$ 600