CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income	$ 26,145	$ 22,467	$ 58,136
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, amortization and impairment	43,765	39,802	37,634
Amortization of discounts, fees and deferred financing costs	2,825	1,981	2,031
Loss on early extinguishment of debt	0	0	526
Stock-based compensation	4,745	5,721	15,872
Premium paid for interest rate cap agreements	0	0	(1,186)
Deferred taxes	121	2,350	11,299
Change in fair value of income tax receivable agreement	(221)	(2,673)	(7,234)
Loss (gain) on disposal of assets, net	529	80	(27)
Other non-cash charges, net	317	119	1,217
Change in operating assets and liabilities, net of acquisitions:
Accounts receivable	(2,624)	13,118	17,568
Inventories	3,659	(6,799)	11
Prepaid expenses and other current assets	2,072	(2,340)	(6,353)
Other assets	(5,377)	(5,712)	(1,325)
Right-of-use assets and operating lease liabilities	(2,067)	0	0
Accounts payable	(9,543)	25,661	2,294
Accrued compensation and benefits	2,609	5,602	(118)
Accrued expenses and other liabilities	(28,134)	7,027	(1,797)
Cash provided by operating activities	38,821	106,404	128,548
Investing activities
Purchases of property, equipment and intangible assets	(23,122)	(44,960)	(36,073)
Proceeds from asset sales	9,400	2,502	2,325
Cash paid for acquisitions	(6,590)	(388)	(1,555)
Cash used in investing activities	(20,312)	(42,846)	(35,303)
Financing activities
Net proceeds from issuance of long-term debt	0	0	267,564
Cash paid for financing costs	0	0	(3,914)
Proceeds on term loans, net of discounts and fees	78,299	82,389	49,921
Payments on long-term debt	(54,069)	(90,428)	(327,331)
Dividends and dividend equivalents paid	(50)	(332)	(8,729)
Proceeds from exercise of stock options	10	1,398	2,380
Common stock repurchases for tax withholdings of net settlement of equity awards	0	(417)	0
Repurchases of vested restricted stock awards withheld on net share settlement	(368)	(421)	0
Distributions to noncontrolling interests	(62,987)	(70,960)	(79,478)
Contributions from noncontrolling interests	8,349	7,739	6,522
Purchases of noncontrolling interests	(8,499)	(9,066)	(29,540)
Proceeds from sales of additional noncontrolling interests	0	229	66
Cash used in financing activities	(39,315)	(79,869)	(122,539)
(Decrease) increase in cash	(20,806)	(16,311)	(29,294)
Cash and restricted cash at beginning of year	55,300	71,611	100,905
Cash and restricted cash at end of year	34,494	55,300	71,611
Supplemental Disclosure of Cash Flow Information
Non-cash equity impacts of the sale or closure of clinics	1,702	610	(19)
Non-cash equity contributions	4,655	0	0
Cash paid for income taxes	2,159	2,635	1,885
Cash paid for interest	34,152	30,504	26,812
Supplemental Disclosure of Non-Cash Flow Information
Assets acquired under capital lease obligations	0	6,168	0
Change in liability accrued for dividend equivalent payments	45	(478)	2,880
Contributions from noncontrolling interests in the form of a receivable	25	148	0
Liability accrued for purchases of noncontrolling interests	0	0	3,696
Non-cash portion of long-term debt refinancing	$ 0	$ 0	$ 167,808