Segment Reporting - Revenues by Reportable Segment (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment									3
Segment Reporting Information [Line Items]
Revenues	$ 306,001	$ 282,682	$ 289,681	$ 267,074	$ 263,322	$ 239,599	$ 232,827	$ 224,143	$ 1,145,438	$ 959,891	$ 403,289
Surgical facility services
Segment Reporting Information [Line Items]
Revenues									1,042,097	884,144	339,309
Ancillary services
Segment Reporting Information [Line Items]
Revenues									90,836	61,175	49,787
Optical services
Segment Reporting Information [Line Items]
Revenues									$ 12,505	$ 14,572	$ 14,193