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Stock Compensation (Details)
$ / shares in Units, $ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2018
USD ($)
trading_day
$ / shares
shares
Dec. 30, 2017
USD ($)
$ / shares
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Stock price (in dollars per share) $ 32.59 $ 9.76  
Expected volatility 125.57% 33.80%  
Risk-free interest rate 1.77% 1.55%  
Expected term (in years) 8 days 16 days  
Stock Appreciation Rights (SARs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average exercise price (in dollars per share) $ 7.00    
Options outstanding (in shares) | shares 445,000    
Deferred compensation liability | $ $ 9.9 $ 1.0  
Weighted average exercise price, trading day average | trading_day 20    
Payable within thirty days of the vesting date | Stock Appreciation Rights (SARs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period     30 days
Payable within one year of vesting date | Stock Appreciation Rights (SARs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period     1 year