Income Taxes (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Income tax benefit $ (116) $ (2,786)  
Effective income tax rate (as a percent) 14.00% 142.00%  
U.S. federal statutory rate (as a percent) 21.00%   34.00%
Provisional, one-time tax expense     $ 9,000
Valuation allowance decrease     9,000
Net tax expense or benefit     0
AMT credit carryforwards, one-time tax benefit     400
AMT valuation allowance decrease     400
Tax benefit arising from Tax Act     200
Unrepatriated foreign earnings, incomplete accounting for tax effect $ 0    
State      
Net operating losses     67,800
Tax credit carryforwards     2,800
Federal      
Net operating losses     66,700
Tax credit carryforwards     $ 6,600