Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Taxes
Income tax provision	$ 2,970	$ (2,611)	$ 6,528	$ (2,600)
Tax benefit recognized upon the expiration of statute of limitation	300		300
Interest and penalties previously accrued credited to interest expenses	$ 200		$ 200
Deferred tax assets valuation allowance					$ 90,300
Federal statutory tax rate			21.00%		35.00%