Related Party Transactions - Narrative (Details)  | 
1 Months Ended | 3 Months Ended | 12 Months Ended | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 
 Oct. 30, 2015  
USD ($)  
shares 
 | 
 Oct. 28, 2015  
USD ($) 
 | 
 Aug. 04, 2015  
USD ($)  
shares 
 | 
 Jul. 31, 2015  
USD ($) 
 | 
 May 13, 2015  
USD ($)  
shares 
 | 
 May 07, 2015  
USD ($) 
 | 
Apr. 29, 2015  | 
 Feb. 19, 2015  
USD ($) 
 | 
 Jan. 22, 2015  
shares 
 | 
Feb. 28, 2013  | 
 Dec. 31, 2014  
USD ($) 
 | 
 Dec. 31, 2017  
USD ($) 
 | 
 Dec. 31, 2016  
USD ($)  
shares 
 | 
 Dec. 31, 2015  
USD ($) 
 | 
|
| Related Party Transaction [Line Items] | ||||||||||||||
| Royalty rate | 2.50% | |||||||||||||
| Termination notice, number of days | 120 days | |||||||||||||
| Repurchase of common stock | $ 5,000,000.0 | $ 5,000,000.0 | $ 5,000,000.0 | $ 23,704,000 | $ 16,071,000 | |||||||||
| Repurchase of common stock (in shares) | shares | 106,264 | 162,442 | 186,519 | 903,031 | ||||||||||
| Director | George Broady | ||||||||||||||
| Related Party Transaction [Line Items] | ||||||||||||||
| Treasury stock acquired rate | 0.4066 | 0.4085 | 0.4286 | |||||||||||
| Repurchase of common stock | $ 1,100,000 | |||||||||||||
| Repurchase of common stock (in shares) | shares | 91,817 | |||||||||||||
| Shares repurchased per trading day | shares | 5,000 | |||||||||||||
| Director | George K. Broady | ||||||||||||||
| Related Party Transaction [Line Items] | ||||||||||||||
| Repurchase of common stock | $ 1,400,000 | $ 1,500,000 | $ 1,500,000 | |||||||||||
| Soothe | Broady Health Sciences | ||||||||||||||
| Related Party Transaction [Line Items] | ||||||||||||||
| Royalty rate | 2.50% | |||||||||||||
| Royalty expense | $ 11,700 | $ 1,400 | $ 3,400 | 7,000 | ||||||||||
| Termination notice, number of days | 120 days | |||||||||||||
| ReStore [Member] | Broady Health Sciences | ||||||||||||||
| Related Party Transaction [Line Items] | ||||||||||||||
| Royalty expense | $ 306,000 | $ 475,000 | $ 555,000 | |||||||||||