Significant Accounting Policies - Schedule of Revenues by Sources (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]                      
Increase of revenue as result of changes in estimates to third-party settlements                 $ 6,800 $ 2,300  
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Total net revenues $ 306,001 $ 282,682 $ 289,681 $ 267,074 $ 263,322 $ 239,599 $ 232,827 $ 224,143 1,145,438 959,891 $ 403,289
Healthcare Organization, Patient Service                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Patient service revenues                 $ 1,124,604 $ 940,711 $ 388,073
Healthcare Organization, Patient Service | Customer | Revenue                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Revenue by service type as a percentage of total revenues                 100.00% 100.00% 100.00%
Optical services                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Other service revenues                 $ 12,505 $ 14,572 $ 14,193
Other                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Other service revenues                 8,329 4,608 1,023
Private insurance | Healthcare Organization, Patient Service                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Patient service revenues                 $ 579,662 $ 516,739 $ 202,172
Private insurance | Healthcare Organization, Patient Service | Customer | Revenue                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Revenue by service type as a percentage of total revenues                 51.50% 55.00% 52.10%
Government | Healthcare Organization, Patient Service                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Patient service revenues                 $ 448,953 $ 359,471 $ 134,041
Government | Healthcare Organization, Patient Service | Customer | Revenue                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Revenue by service type as a percentage of total revenues                 39.90% 38.20% 34.50%
Self-pay | Healthcare Organization, Patient Service                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Patient service revenues                 $ 19,817 $ 16,190 $ 13,645
Self-pay | Healthcare Organization, Patient Service | Customer | Revenue                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Revenue by service type as a percentage of total revenues                 1.80% 1.70% 3.50%
Other | Healthcare Organization, Patient Service                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Patient service revenues                 $ 76,172 $ 48,311 $ 38,215
Other | Healthcare Organization, Patient Service | Customer | Revenue                      
Health Care Organization, Receivable and Revenue Disclosures [Line Items]                      
Revenue by service type as a percentage of total revenues                 6.80% 5.10% 9.90%