| Intangible Assets | 
 
 
 The carrying amount and accumulated amortization of intangible
 assets as of March 31, 2016 and December 31, 2015, are as follows
 (in thousands): 
   
 
 |  |  |  |  |  |  |  |  |  |  |  |  |  |  
 |  |  | March 31, 2016 |  |  
 |  |  | Gross Assets
 |  |  | Accumulated Amortization
 |  |  | Net |  |  
 | 
 Nonamortizable intangible assets |  |  |  |  |  |  |  |  |  |  |  |  |  
 | 
 Trade names |  | $ | 2,000 |  |  | $ | — |  |  | $ | 2,000 |  |  
 | 
 Amortizable intangible assets |  |  |  |  |  |  |  |  |  |  |  |  |  
 | 
 Trade names |  |  | 23 |  |  |  | 21 |  |  |  | 2 |  |  
 | 
 Physician and customer relationships |  |  | 32,865 |  |  |  | 17,493 |  |  |  | 15,372 |  |  
 | 
 Physician and customer relationships - Ciscura |  |  | 3,394 |  |  |  | 156 |  |  |  | 3,238 |  |  
 | 
 Non-competition agreements |  |  | 1,094 |  |  |  | 961 |  |  |  | 133 |  |  
 | 
 Software |  |  | 11,717 |  |  |  | 629 |  |  |  | 11,088 |  |  
 |  |  | 
   | 
   |  |  | 
   | 
   |  |  | 
   | 
   |  |  
 | 
 Total nonamortizable and amortizable intangible assets |  | $ | 51,093 |  |  | $ | 19,260 |  |  | $ | 31,833 |  |  
 |  |  | 
   | 
   |  |  | 
   | 
   |  |  | 
   | 
   |  |  
 |  |  |  
 |  |  | December 31, 2015 |  |  
 |  |  | Gross Assets
 |  |  | Accumulated Amortization
 |  |  | Net |  |  
 | 
 Nonamortizable intangible assets |  |  |  |  |  |  |  |  |  |  |  |  |  
 | 
 Trade names |  | $ | 2,000 |  |  | $ | — |  |  | $ | 2,000 |  |  
 | 
 Amortizable intangible assets |  |  |  |  |  |  |  |  |  |  |  |  |  
 | 
 Trade names |  |  | 23 |  |  |  | 15 |  |  |  | 8 |  |  
 | 
 Physician and customer relationships |  |  | 32,865 |  |  |  | 16,946 |  |  |  | 15,919 |  |  
 | 
 Physician and customer relationships - Ciscura |  |  | 3,393 |  |  |  | 103 |  |  |  | 3,290 |  |  
 | 
 Non-competition agreements |  |  | 1,094 |  |  |  | 930 |  |  |  | 164 |  |  
 | 
 Software |  |  | 11,942 |  |  |  | 1,789 |  |  |  | 10,153 |  |  
 |  |  | 
   | 
   |  |  | 
   | 
   |  |  | 
   | 
   |  |  
 | 
 Total nonamortizable and amortizable intangible assets |  | $ | 51,317 |  |  | $ | 19,783 |  |  | $ | 31,534 |  |  
 |  |  | 
   | 
   |  |  | 
   | 
   |  |  | 
   | 
   |  |  
 Amortization expense for the three months ended March 31, 2016 was
 $0.9 million compared to $0.6 million for the three months ended
 March 31, 2015. Expected annual amortization expense for
 intangible assets recorded as of March 31, 2016, is as follows (in
 thousands): 
   
 
 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
 |  |  | 4/1- 12/31/2016
 |  |  | 2017 |  |  | 2018 |  |  | 2019 |  |  | 2020 |  |  | 2021 and thereafter
 |  |  
 | 
 Amortization expense |  | $ | 4,158 |  |  | $ | 5,301 |  |  | $ | 4,936 |  |  | $ | 5,451 |  |  | $ | 2,590 |  |  | $ | 7,397 |  |  |