Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Income Taxes
Income tax provision	$ 799	$ 2,970	$ 1,271	$ 6,528
Decrease in income tax	2,200		5,300
Decrease in income tax due to decrease in pretax income	3,400		5,700
Decrease in pretax income	16,300		27,200
Increase in valuation allowance	900
Tax benefit	300		(400)
Deferred tax assets	70,598		70,598		$ 71,939
Deferred tax assets valuation allowance	$ 7,700		$ 7,700		$ 6,800