Segment Disclosures - Summary of Operating Performance of Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 107,298	$ 96,829
Segment profit (loss)	(1,130)	(1,681)
Depreciation and amortization	8,304	8,467
System One
Segment Reporting Information [Line Items]
Revenues	81,702	73,274
In-Center
Segment Reporting Information [Line Items]
Revenues	17,357	15,606
Services
Segment Reporting Information [Line Items]
Revenues	5,419	5,050
Operating Segments | System One
Segment Reporting Information [Line Items]
Revenues	82,887	74,661
Segment profit (loss)	21,720	19,848
Depreciation and amortization	5,435	5,634
Operating Segments | In-Center
Segment Reporting Information [Line Items]
Revenues	17,357	15,606
Segment profit (loss)	2,299	2,359
Depreciation and amortization	488	525
Operating Segments | Services
Segment Reporting Information [Line Items]
Revenues	5,419	5,050
Segment profit (loss)	(5,559)	(5,605)
Depreciation and amortization	1,343	1,268
Other
Segment Reporting Information [Line Items]
Revenues	2,820	2,899
Segment profit (loss)	(19,625)	(18,261)
Depreciation and amortization	1,084	1,072
Intersegment Elimination
Segment Reporting Information [Line Items]
Revenues	(1,185)	(1,387)
Segment profit (loss)	35	(22)
Depreciation and amortization	(46)	(32)
Intersegment Elimination | System One
Segment Reporting Information [Line Items]
Revenues	$ 1,185	$ 1,387