Variable Interest Entities (VIEs) - Eliminated Upon Consolidation Included In Accompanying Consolidated Balance Sheets (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents		$ 193,470	$ 103,189	$ 106,892
Restricted cash		0	75
Investment in marketable securities		67,695	116,539
Receivables, net		7,058	11,004
Receivables, net – related party		49,260	48,136
Other receivables		4,297	16,885
Prepaid expenses and other current assets		16,747	10,315
Loans receivable		50	22,925
Total current assets		338,577	329,068
Noncurrent assets
Intangible assets, net		86,985	103,012
Goodwill		239,053	238,505	$ 185,806
Investments in other entities – equity method		43,292	28,427
Restricted cash		500	746
Operating lease right-of-use assets		18,574	14,248
Other assets		18,915	1,681
Total noncurrent assets		478,909	399,645
Total assets	[1]	817,486	728,713
Current liabilities
Accounts payable and accrued expenses		36,143	27,279
Fiduciary accounts payable		9,642	2,027
Medical liabilities		50,330	58,725
Income taxes payable		4,224	4,529
Dividend payable		485	271
Current portion of long-term debt		10,889	9,500
Finance lease liabilities		102	102
Operating lease liabilities		3,177	2,991
Total current liabilities		114,992	105,424
Noncurrent liabilities
Long-term debt, net of current portion		230,211	232,172
Deferred tax liability		10,959	18,269
Finance lease liabilities, net of current portion		311	415
Operating lease liabilities, net of current portion		15,865	11,373
Total noncurrent liabilities		257,346	262,229
Total liabilities	[1]	372,338	367,653
Variable Interest Entity, Primary Beneficiary
Current assets
Cash and cash equivalents		126,158	87,110
Restricted cash		0	75
Investment in marketable securities		67,637	123,948
Receivables, net		5,155	9,300
Receivables, net – related party		46,718	42,976
Other receivables		1,084	744
Prepaid expenses and other current assets		14,813	7,403
Loans receivable		50	6,425
Loans receivable - related parties		0	16,500
Total current assets		261,615	294,481
Noncurrent assets
Land, property and equipment, net		27,599	9,547
Intangible assets, net		69,250	81,439
Goodwill		109,460	108,913
Loans receivable – related parties		4,145	0
Investment in affiliates		225,144	318,315
Investments in other entities – equity method		43,516	28,427
Investment in privately held entities		36,584	1,615
Restricted cash		500	746
Operating lease right-of-use assets		6,298	4,751
Other assets		17,177	1,057
Total noncurrent assets		539,673	554,810
Total assets		801,288	849,291
Current liabilities
Accounts payable and accrued expenses		12,963	11,187
Fiduciary accounts payable		9,642	2,027
Medical liabilities		37,684	49,019
Income taxes payable		4,225	4,530
Dividend payable		485	271
Amount due to affiliate		22,698	28,058
Current portion of long-term debt		201	0
Finance lease liabilities		102	102
Operating lease liabilities		1,242	1,088
Total current liabilities		89,242	96,282
Noncurrent liabilities
Long-term debt, net of current portion		7,379	0
Deferred tax liability		9,144	14,059
Liability for unissued equity shares		0	0
Finance lease liabilities, net of current portion		311	416
Operating lease liabilities, net of current portion		5,242	3,742
Total noncurrent liabilities		22,076	18,217
Total liabilities		$ 111,318	$ 114,499

[1] The Company's consolidated balance sheets include the assets and liabilities of its consolidated variable interest entities ("VIEs"). The consolidated balance sheets include total assets that can be used only to settle obligations of the Company’s consolidated VIEs totaling $801.3 million and $849.3 million as of December 31, 2020 and December 31, 2019, respectively, and total liabilities of the Company’s consolidated VIEs for which creditors do not have recourse to the general credit of the primary beneficiary of $111.3 million and $114.5 million as of December 31, 2020 and December 31, 2019, respectively. See Note 18 – Variable Interest Entities (VIEs) for further detail.