Segment Reporting - Segment Operating Income (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
Segment Reporting Information [Line Items]                      
Total segment adjusted EBITDA                 $ 179,263 $ 158,053 $ 77,034
General and administrative expenses                 (60,246) (55,992) (31,452)
Non-cash stock compensation expense                 2,021 7,502 942
Contingent acquisition compensation expense                 5,092 0 0
Management fee                 0 2,250 2,161
Acquisition related costs                 2,185 1,560 0
Total adjusted EBITDA                 179,263 158,053 77,034
Net income attributable to non-controlling interests $ 21,238 $ 16,672 $ 20,173 $ 17,547 $ 19,355 $ 16,906 $ 17,905 $ 17,250 75,630 71,416 38,845
Depreciation and amortization                 (39,551) (34,545) (15,061)
Interest and other expense, net                 (100,571) (100,980) (62,101)
Income tax (expense) benefit                 (7,095) 148,982 (15,758)
Non-cash stock compensation expense                 (2,021) (7,502) (942)
Contingent acquisition compensation expense                 (5,092) 0 0
Termination of management agreement and IPO costs                 0 (5,834) 0
Management fee                 0 (2,250) (2,161)
Merger transaction, integration and practice acquisition costs                 (11,617) (20,579) (21,690)
Gain on litigation settlement                 14,101 0 0
(Loss) gain on disposal or impairment of long-lived assets, net                 (2,355) 2,097 (1,804)
Tax receivable agreement expense                 (3,733) (119,911) 0
Loss on debt refinancing                 (11,876) (16,102) (23,414)
Net income (loss) $ 38,100 $ 14,334 $ 22,293 $ 10,357 $ 36,094 $ 13,784 $ 12,479 $ 10,488 85,083 72,845 (27,052)
Merger transaction and integration costs                 8,738 17,920 21,690
Practice acquisition costs                 2,879 2,659  
Operating Segments                      
Segment Reporting Information [Line Items]                      
Total segment adjusted EBITDA                 230,211 202,733 105,383
Total adjusted EBITDA                 230,211 202,733 105,383
Operating Segments | Surgical facility services                      
Segment Reporting Information [Line Items]                      
Total segment adjusted EBITDA                 214,218 180,113 83,149
Total adjusted EBITDA                 214,218 180,113 83,149
Operating Segments | Ancillary services                      
Segment Reporting Information [Line Items]                      
Total segment adjusted EBITDA                 12,685 18,715 18,354
Total adjusted EBITDA                 12,685 18,715 18,354
Operating Segments | Optical services                      
Segment Reporting Information [Line Items]                      
Total segment adjusted EBITDA                 3,308 3,905 3,880
Total adjusted EBITDA                 $ 3,308 $ 3,905 $ 3,880