Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)

v3.10.0.1
Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)
$ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2018
USD ($)
Segment
Dec. 31, 2017
USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]    
Standard warranty period offered 3 years  
Cash payments received in advance of satisfying distinct performance obligation $ 4,914  
Performance obligation partially offset of revenue recognized $ 992  
Rental revenue earned 30-day period  
Number of operating segments | Segment 1  
Number of reportable segments | Segment 1  
Lifetime Warranties | Direct-to-Consumer    
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]    
Sales revenue $ 14,742 $ 10,820