Annual report pursuant to Section 13 and 15(d)

Litigation and Related Matters (Details)

v3.8.0.1
Litigation and Related Matters (Details) - USD ($)
$ in Millions
1 Months Ended 3 Months Ended 12 Months Ended
May 15, 2017
Jul. 13, 2016
May 16, 2016
Jul. 06, 2015
Jul. 31, 2015
Jun. 30, 2018
Dec. 31, 2013
Dec. 31, 2017
Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]                  
Environmental liabilities               $ 0.0 $ 0.0
Armstrong Kushan, multilayered wood flooring imports from China                  
Loss Contingencies [Line Items]                  
Countervailing duties rate             0.98%    
Antidumping duties rate       3.31%     0.00%    
Armstrong Kushan, Multi-layered Wood Flooring Imports from China, Second Administrative Review                  
Loss Contingencies [Line Items]                  
Countervailing duties rate         0.99%        
Antidumping duties rate         13.74%        
Armstrong Kushan, Multi-layered Wood Flooring Imports from China, Second Administrative Review | Accounts payable and accrued expenses                  
Loss Contingencies [Line Items]                  
Estimated litigation liability               4.8  
Armstrong Kushan, Multi-layered Wood Flooring Imports from China, Third Administrative Review                  
Loss Contingencies [Line Items]                  
Countervailing duties rate     1.38%            
Antidumping duties rate   17.37%              
Armstrong Kushan, Multi-layered Wood Flooring Imports from China, Third Administrative Review | Accounts payable and accrued expenses                  
Loss Contingencies [Line Items]                  
Estimated litigation liability               $ 6.0  
Armstrong Kushan, Multi-layered Wood Flooring Imports from China, Fourth Administrative Review                  
Loss Contingencies [Line Items]                  
Countervailing duties rate 1.06%                
Scenario, Forecast | Armstrong Kushan, Multi-layered Wood Flooring Imports from China, Fourth Administrative Review                  
Loss Contingencies [Line Items]                  
Countervailing duties rate           0.89%      
Antidumping duties rate           0.00%