Goodwill (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Beginning balance, as restated	[1]	$ 195,373	$ 171,740
Goodwill acquired during the period		31,419	23,437	[1]
Goodwill adjustments for purchase price allocation of business acquired		14	376	[1]
Goodwill written-off - closed clinics		0	(180)	[1]
Ending balance		$ 226,806	$ 195,373	[1]

[1] as restated