Oscar Health (OSCR) 10-Q 12 Nov 21 2021 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2021	Oct. 29, 2021
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Sep. 30, 2021
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-40154
Entity Registrant Name	Oscar Health, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-1315570
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Central Index Key	0001568651
Entity Address, Address Line One	75 Varick Street, 5th Floor
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10013
City Area Code	(646)
Local Phone Number	403-3677
Title of 12(b) Security	Class A Common Stock, $0.00001 par value per share
Trading Symbol	OSCR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		174,400,003
Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		35,115,807

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 1,076,699	$ 826,326
Short-term investments	586,954	366,387
Premium and other receivables	117,534	65,322
Risk adjustment transfer receivable	43,099	31,157
Accrued investment income	3,086	1,862
Balances due from reinsurance programs	413,789	579,393
Total current assets	2,241,161	1,870,447
Property, equipment, and capitalized software, net	43,376	35,812
Long-term investments	838,273	325,740
Restricted deposits	27,757	26,478
Other assets	18,828	13,136
Net deferred tax asset	485	493
Total Assets	3,169,880	2,272,106
Current Liabilities:
Benefits payable	497,324	311,914
Risk adjustment transfer payable	613,230	716,370
Premium deficiency reserve	69,432	84,571
Unearned premiums	56,175	71,904
Accounts payable and accrued liabilities	159,196	137,524
Reinsurance payable	221,311	343,313
Total current liabilities	1,616,668	1,665,596
Long-term debt	0	142,487
Warrant liabilities	0	15,005
Total liabilities	1,616,668	1,823,088
Commitments and contingencies (Note 15)
Convertible Preferred Stock, $0.00001 par value; 407,156,831 shares authorized; 400,904,302 shares issued and outstanding as of December 31, 2020	0	1,744,911
Stockholders' Equity (Deficit)
Preferred stock, $0.00001 par value; 82,500,000 shares authorized, none issued or outstanding as of September 30, 2021	0	0
Common stock		2
Treasury stock (314,600 shares as of September 30, 2021 and December 31, 2020)	(2,923)	(2,923)
Additional paid-in capital	3,356,406	133,255
Accumulated deficit	(1,800,290)	(1,427,106)
Accumulated other comprehensive income (loss)	17	879
Total Stockholders’ Equity (Deficit)	1,553,212	(1,295,893)
Total Liabilities, Convertible Preferred Stock and Stockholders' Equity (Deficit)	3,169,880	$ 2,272,106
Class A
Stockholders' Equity (Deficit)
Common stock	2
Class B
Stockholders' Equity (Deficit)
Common stock	$ 0

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Convertible preferred stock, par value (in dollars per share)		$ 0.00001
Convertible preferred stock, shares authorized		407,156,831
Convertible preferred stock, shares issued		400,904,302
Convertible preferred stock, shares outstanding	0	400,904,302
Preferred stock, par value (in dollars per share)	$ 0.00001
Preferred stock, shares authorized	82,500,000
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Treasury stock (in shares)	314,600	314,600
Class A
Common stock, par value (in dollars per share)	$ 0.00001
Common stock, shares authorized	825,000,000
Common stock, shares issued	174,056,898
Common stock, shares outstanding	174,056,898
Class B
Common stock, par value (in dollars per share)	$ 0.00001
Common stock, shares authorized	82,500,000
Common stock, shares issued	35,115,807
Common stock, shares outstanding	35,115,807
Series A common stock
Common stock, par value (in dollars per share)		$ 0.00001
Common stock, shares authorized		680,000,000
Common stock, shares issued		8,291,917
Common stock, shares outstanding		8,291,917
Series B common stock
Common stock, par value (in dollars per share)		$ 0.00001
Common stock, shares authorized		69,487,963
Common stock, shares issued		23,162,654
Common stock, shares outstanding		23,162,654
Series C common stock
Common stock, par value (in dollars per share)		$ 0.00001
Common stock, shares authorized		10,000,000
Common stock, shares issued		0
Common stock, shares outstanding		0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue
Premiums before ceded reinsurance	$ 673,460	$ 414,505	$ 2,007,486	$ 1,232,493
Reinsurance premiums ceded	(231,717)	(315,360)	(669,047)	(934,373)
Premiums earned	441,743	99,145	1,338,439	298,120
Investment income and other revenue	2,236	2,555	4,209	7,008
Total revenue	443,979	101,700	1,342,648	305,128
Operating Expenses
Claims incurred, net	453,576	85,392	1,141,503	225,120
Other insurance costs	111,302	38,674	285,929	119,222
General and administrative expenses	61,267	36,546	175,240	104,379
Federal and state assessments	35,453	20,469	102,841	61,724
Health insurance industry fee	0	4,813	0	14,438
Premium deficiency reserve release	(4,675)	(4,064)	(15,139)	(4,326)
Total operating expenses	656,923	181,830	1,690,374	520,557
Loss from operations	(212,944)	(80,130)	(347,726)	(215,429)
Interest expense	398	0	4,323	0
Loss on extinguishment of debt	0	0	20,178	0
Loss before income taxes	(213,342)	(80,130)	(372,227)	(215,429)
Income tax (benefit) provision	(597)	(998)	957	1,526
Net loss	$ (212,745)	$ (79,132)	$ (373,184)	$ (216,955)
Earnings (Loss) per Share
Net loss per share, basic (in dollars per share)	$ (1.02)	$ (2.72)	$ (2.21)	$ (7.50)
Net loss per share, diluted (in dollars per share)	$ (1.02)	$ (2.72)	$ (2.21)	$ (7.50)
Weighted average common shares outstanding, basic	208,159,343	29,042,932	168,585,157	28,941,215
Weighted-average common shares outstanding, diluted	208,159,343	29,042,932	168,585,157	28,941,215
Stock-based compensation expense	$ 20,640	$ 7,287	$ 58,028	$ 21,984

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (212,745)	$ (79,132)	$ (373,184)	$ (216,955)
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on securities available for sale	57	(1,002)	(862)	1,219
Comprehensive loss	$ (212,688)	$ (80,134)	$ (374,046)	$ (215,736)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Common StockClass A	Common StockClass B	Treasury Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2019	335,625,349
Beginning balance at Dec. 31, 2019	$ 1,295,744
Ending balance (in shares) at Mar. 31, 2020	335,625,349
Ending balance at Mar. 31, 2020	$ 1,295,744
Beginning balance (in shares) at Dec. 31, 2019		28,840,849
Beginning balance at Dec. 31, 2019	(945,138)	$ 2			$ (2,923)	$ 70,673	$ (1,012,863)	$ (27)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)		55,226
Issuance of common stock upon exercise of options	443					443
Stock-based compensation expense	8,096					8,096
Net unrealized gains (losses) on securities available for sale	1,529							1,529
Net loss	(96,879)						(96,879)
Ending balance (in shares) at Mar. 31, 2020		28,896,075
Ending balance at Mar. 31, 2020	$ (1,031,949)	$ 2			(2,923)	79,212	(1,109,742)	1,502
Beginning balance (in shares) at Dec. 31, 2019	335,625,349
Beginning balance at Dec. 31, 2019	$ 1,295,744
Ending balance (in shares) at Sep. 30, 2020	372,912,630
Ending balance at Sep. 30, 2020	$ 1,506,687
Beginning balance (in shares) at Dec. 31, 2019		28,840,849
Beginning balance at Dec. 31, 2019	(945,138)	$ 2			(2,923)	70,673	(1,012,863)	(27)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net unrealized gains (losses) on securities available for sale	1,219
Net loss	(216,955)
Ending balance (in shares) at Sep. 30, 2020		29,232,999
Ending balance at Sep. 30, 2020	$ (1,136,887)	$ 2			(2,923)	94,660	(1,229,818)	1,192
Beginning balance (in shares) at Mar. 31, 2020	335,625,349
Beginning balance at Mar. 31, 2020	$ 1,295,744
Increase (Decrease) in Temporary Equity [Roll Forward]
Stock issued (in shares)	37,287,281
Stock Issued	$ 210,943
Ending balance (in shares) at Jun. 30, 2020	372,912,630
Ending balance at Jun. 30, 2020	$ 1,506,687
Beginning balance (in shares) at Mar. 31, 2020		28,896,075
Beginning balance at Mar. 31, 2020	(1,031,949)	$ 2			(2,923)	79,212	(1,109,742)	1,502
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)		41,972
Issuance of common stock upon exercise of options	322					322
Stock-based compensation expense	6,601					6,601
Net unrealized gains (losses) on securities available for sale	692							692
Net loss	(40,944)						(40,944)
Ending balance (in shares) at Jun. 30, 2020		28,938,047
Ending balance at Jun. 30, 2020	$ (1,065,278)	$ 2			(2,923)	86,135	(1,150,686)	2,194
Ending balance (in shares) at Sep. 30, 2020	372,912,630
Ending balance at Sep. 30, 2020	$ 1,506,687
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)		294,952
Issuance of common stock upon exercise of options	1,238					1,238
Stock-based compensation expense	7,287					7,287
Net unrealized gains (losses) on securities available for sale	(1,002)							(1,002)
Net loss	(79,132)						(79,132)
Ending balance (in shares) at Sep. 30, 2020		29,232,999
Ending balance at Sep. 30, 2020	$ (1,136,887)	$ 2			(2,923)	94,660	(1,229,818)	1,192
Beginning balance (in shares) at Dec. 31, 2020	400,904,302
Beginning balance at Dec. 31, 2020	$ 1,744,911
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of pre-IPO shares to Class A and Class B common stock (in shares)	(400,904,302)
Conversion of pre-IPO shares to Class A and Class B common stock	$ (1,744,911)
Ending balance (in shares) at Mar. 31, 2021	0
Ending balance at Mar. 31, 2021	$ 0
Beginning balance (in shares) at Dec. 31, 2020		31,409,202	0	0
Beginning balance at Dec. 31, 2020	(1,295,893)	$ 2	$ 0	$ 0	(2,923)	133,255	(1,427,106)	879
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of pre-IPO shares to Class A and Class B common stock (in shares)		(31,409,202)	130,280,651	35,115,807
Conversion of pre-IPO shares to Class A and Class B common stock	1,744,910	$ (2)	$ 1			1,744,911
Issuance of common stock upon IPO, net of underwriting discount (in shares)			36,391,946
Issuance of common stock upon IPO, net of underwriting discount	1,338,875		$ 1			1,338,874
Issuance of common stock upon exercise of warrants and call options (in shares)			1,115,973
Issuance of common stock upon exercise of warrants and call options	37,071					37,071
Issuance of common stock upon exercise of options (in shares)			4,272,060
Issuance of common stock upon exercise of options	29,805					29,805
Stock-based compensation expense	19,115					19,115
Net unrealized gains (losses) on securities available for sale	(275)							(275)
Net loss	(87,371)						(87,371)
Ending balance (in shares) at Mar. 31, 2021		0	172,060,630	35,115,807
Ending balance at Mar. 31, 2021	$ 1,786,237	$ 0	$ 2	$ 0	(2,923)	3,303,031	(1,514,477)	604
Beginning balance (in shares) at Dec. 31, 2020	400,904,302
Beginning balance at Dec. 31, 2020	$ 1,744,911
Ending balance (in shares) at Sep. 30, 2021	0
Ending balance at Sep. 30, 2021	$ 0
Beginning balance (in shares) at Dec. 31, 2020		31,409,202	0	0
Beginning balance at Dec. 31, 2020	$ (1,295,893)	$ 2	$ 0	$ 0	(2,923)	133,255	(1,427,106)	879
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)	5,990,310
Net unrealized gains (losses) on securities available for sale	$ (862)
Net loss	(373,184)
Ending balance (in shares) at Sep. 30, 2021		0	174,056,898	35,115,807
Ending balance at Sep. 30, 2021	$ 1,553,212	$ 0	$ 2	$ 0	(2,923)	3,356,406	(1,800,290)	17
Beginning balance (in shares) at Mar. 31, 2021	0
Beginning balance at Mar. 31, 2021	$ 0
Ending balance (in shares) at Jun. 30, 2021	0
Ending balance at Jun. 30, 2021	$ 0
Beginning balance (in shares) at Mar. 31, 2021		0	172,060,630	35,115,807
Beginning balance at Mar. 31, 2021	1,786,237	$ 0	$ 2	$ 0	(2,923)	3,303,031	(1,514,477)	604
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)			393,581
Issuance of common stock upon exercise of options	3,033					3,033
Stock-based compensation expense	18,273					18,273
Net unrealized gains (losses) on securities available for sale	(644)							(644)
Net loss	(73,068)						(73,068)
Ending balance (in shares) at Jun. 30, 2021		0	172,454,211	35,115,807
Ending balance at Jun. 30, 2021	$ 1,733,831	$ 0	$ 2	$ 0	(2,923)	3,324,337	(1,587,545)	(40)
Ending balance (in shares) at Sep. 30, 2021	0
Ending balance at Sep. 30, 2021	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)			1,602,687
Issuance of common stock upon exercise of options	11,429					11,429
Stock-based compensation expense	20,640					20,640
Net unrealized gains (losses) on securities available for sale	57							57
Net loss	(212,745)						(212,745)
Ending balance (in shares) at Sep. 30, 2021		0	174,056,898	35,115,807
Ending balance at Sep. 30, 2021	$ 1,553,212	$ 0	$ 2	$ 0	$ (2,923)	$ 3,356,406	$ (1,800,290)	$ 17

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (373,184)	$ (216,955)
Adjustments to reconcile net loss to net cash used in operating activities:
Deferred taxes	8	0
Net realized gain on sale of financial instruments	(268)	(936)
(Gain) loss on fair value of warrant liabilities	12,856	(509)
Depreciation and amortization expense	10,635	7,990
Amortization of debt issuance costs	329	0
Stock-based compensation expense	58,028	21,984
Investment amortization, net of accretion	5,490	1,511
Debt extinguishment loss	20,178	0
(Increase) / decrease in:
Premium and other receivables	(52,211)	(37,806)
Risk adjustment transfer receivable	(11,941)	(21,303)
Accrued investment income	(1,224)	(484)
Balances due from reinsurance programs	165,604	(127,519)
Other assets	(5,210)	(7,517)
Increase / (decrease) in:
Benefits payable	185,410	119,955
Unearned premiums	(15,729)	32,315
Premium deficiency reserve	(15,139)	(4,326)
Accounts payable and accrued liabilities	25,287	26,050
Reinsurance payable	(122,003)	109,143
Risk adjustment transfer payable	(103,140)	232,156
Net cash (used in) provided by operating activities	(216,224)	133,749
Cash flows from investing activities:
Purchase of investments	(1,525,908)	(838,927)
Sale of investments	422,030	370,133
Maturity of investments	364,254	120,860
Purchase of property, equipment and capitalized software	(18,679)	(10,696)
Change in restricted deposits	3,625	(723)
Net cash used in investing activities	(754,678)	(359,353)
Cash flows from financing activities:
Debt prepayment	(153,173)	0
Debt extinguishment costs	(12,994)	0
Proceeds from IPO, net of underwriting discounts	1,348,321	0
Offering costs from IPO	(9,447)	0
Convertible preferred stock and call option issuances	0	224,431
Proceeds from exercise of warrants and call options	9,191	0
Proceeds from exercise of stock options	43,841	2,003
Net cash provided by financing activities	1,225,739	226,434
Increase in cash, cash equivalents and restricted cash equivalents	254,837	830
Cash, cash equivalents, restricted cash and cash equivalents—beginning of period	843,105	353,380
Cash, cash equivalents, restricted cash and cash equivalents—end of period	1,097,942	354,210
Cash and cash equivalents	1,076,699	337,409
Restricted cash and cash equivalents included in restricted deposits	21,243	16,801
Total cash, cash equivalents and restricted cash and cash equivalents	1,097,942	354,210
Supplemental Disclosures:
Interest payments	3,994	0
Income tax payments	936	1,918
Non-cash investing and financing activities:
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	1,744,914	0
Net exercise of preferred stock warrants to preferred stock upon initial public offering	28,248	0
Adjustment to fair value of preferred stock warrant liability upon initial public offering	$ 13,243	$ 0

ORGANIZATION

ORGANIZATION	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION	ORGANIZATION Oscar Health, Inc. ("Oscar" or the "Company") is the first health insurance company built around a full stack technology platform and a relentless focus on serving its members. Headquartered in New York City, Oscar offers Individual & Family, Small Group and Medicare Advantage plans. The Company operates as one segment to sell insurance to its members directly, as well as through the state-run health care exchanges formed in conjunction with the Patient Protection and Affordable Care Act ("ACA") via its health insurance subsidiaries. The Company provides plans in the Medicare Advantage program to adults who are age 65 and older and eligible for traditional Medicare but who instead select coverage through a private market plan. The Company has also partnered with Cigna through the Cigna + Oscar partnership, which unites Oscar’s highly-differentiated member experience with Cigna’s broad provider networks, to exclusively serve the Small Group employer market. In April 2021, the Company announced the launch of + Oscar, its tech-driven platform offering designed to help healthcare clients drive improved efficiency, growth and superior engagement with their members and patients. Initial Public Offering On March 2, 2021, the Company's registration statement on Form S-1 (the “IPO Registration Statement”) related to its initial public offering (“IPO”) was declared effective and the Company’s Class A common stock, par value $0.00001 per share (the “Class A common stock”) began trading on the New York Stock Exchange on March 3, 2021. On March 5, 2021, the Company completed its IPO, in which the Company sold 36,391,946 shares of Class A common stock at a price to the public of $39.00 per share. The Company received aggregate net proceeds of $1.3 billion after deducting underwriting discounts and commissions of $71.0 million. The Company used a portion of the net proceeds of the IPO to repay in full outstanding borrowings, including fees and expenses, under the Term Loan Facility. Refer to Note 9 - Debt and Warrants for more information. The Company's Class A common stock is traded on the New York Stock Exchange under the symbol "OSCR." Reclassification and Reverse Stock Split In connection with its IPO, on March 3, 2021, the Company filed an amended and restated certificate of incorporation (the “Amended and Restated Certificate of Incorporation”) with the Secretary of State of the State of Delaware, which effected a reclassification of the Company’s issued and outstanding share capital and a one-for-three reverse stock split. Upon conversion of all outstanding shares of convertible preferred stock, and upon filing of the Company’s Amended and Restated Certificate of Incorporation, all outstanding shares of each series of the Company’s convertible preferred stock and common stock issued and outstanding prior to the IPO converted and/or were reclassified into an aggregate of 132,760,639 shares of Class A common stock and 35,335,579 shares of Class B common stock, par value $0.00001 per share (the “Class B common stock”), and 943,800 shares of common stock held in treasury were reclassified into an aggregate of 314,600 shares of Class A common stock. In accordance with accounting principles generally accepted in the United States (“ U.S. GAAP”), all shares of common stock and per share data that are presented in this Quarterly Report on Form 10-Q have been adjusted to reflect the reclassification and reverse stock split on a retroactive basis for all periods presented. Shares of convertible preferred stock presented in this Quarterly Report on Form 10-Q have not been adjusted for the reclassification or reverse stock split, as these shares were converted to common stock prior to the reclassification and reverse stock split. For additional information, see Note 11 - Stockholders’ Equity. Basis of Presentation The accompanying interim condensed consolidated financial statements of the Company are unaudited. These interim unaudited condensed consolidated financial statements have been prepared in accordance with U.S. GAAP, and the applicable rules and regulations of the Securities and Exchange Commission ("SEC") for interim financial information. As such, these financial statements do not include all information and footnotes required by U.S. GAAP for complete financial statements. These condensed consolidated financial statements are unaudited; however, in the opinion of management, they reflect all adjustments consisting only of normal recurring adjustments necessary to state fairly the information presented for the periods presented in conformity with U.S. GAAP applicable to interim periods. The results of operations for the interim periods presented are not necessarily indicative of results for the full year or future periods. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the related notes thereto as of and for the year ended December 31, 2020 included in the prospectus dated March 2, 2021 (File No. 333-252809) (the "Prospectus"), as filed with the SEC pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the unaudited consolidated financial statements and accompanying notes. Significant estimates inherent in the preparation of the accompanying unaudited consolidated financial statements include healthcare costs incurred but not yet reported (“IBNR”), reinsurance, premium deficiency reserve (“PDR”), risk adjustment, stock-based compensation, premium receivable allowance and income taxes. Estimates are based on past experience and other considerations reasonable under the circumstances. Actual results may differ materially from these estimates. Additionally, the full extent to which the outbreak of COVID-19 could impact the Company’s business, results of operations and financial condition is still unknown and will depend on future developments, which are highly uncertain and cannot be predicted. However, the Company has made accounting estimates based on the facts and circumstances available as of the reporting date. The Company has not currently experienced significant negative impact to its operations, liquidity or capital resources as a result of the COVID-19 pandemic.

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Sep. 30, 2021
Accounting Changes and Error Corrections [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS The Company currently qualifies as an emerging growth company ("EGC") under the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”) which, amongst other things, allows for reduced disclosure requirements and an extended transition period for the implementation of new or revised accounting pronouncements. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an EGC or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. As of September 30, 2021, the Company has exceeded the maximum annual revenue threshold for EGCs and expects that it will lose EGC status as of December 31, 2021. As a result, the Company will be required to comply with public company disclosure requirements applicable to registrants that have exited EGC status, including the implementation of previously deferred accounting pronouncements, as of December 31, 2021. Accounting Pronouncements - Not Yet Adopted In February 2016, the FASB issued ASU 2016- 02, Leases (Topic 842) . The ASU requires lessees to recognize a right-of-use asset and a lease liability for all leases with an initial term in excess of twelve months. The asset reflects the present value of unpaid lease payments coupled with initial direct costs, prepaid lease payments and lease incentives. The amount of the lease liability is calculated as the present value of unpaid lease payments. The Company is currently in the process of finalizing the key data inputs required to calculate the financial statement impact of the new guidance. The adoption of this guidance was deferred under the extended transition period provided to EGCs. The Company expects to adopt this guidance as of January 1, 2021 in its December 31, 2021 financial statements using the modified retrospective method of adoption. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326) . The ASU provides new guidance for estimating credit losses on certain types of financial instruments by introducing an approach based on expected losses. The Company is currently in the implementation phase of adoption and is evaluating the effects of the standard on its financial statements. The adoption of this guidance was deferred under the extended transition period provided to EGCs. The Company expects to adopt this guidance as of January 1, 2021 in its December 31, 2021 financial statements using the modified retrospective method of adoption. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes . The amendments in this ASU simplify the accounting for income taxes by removing certain exceptions for investments, intra-period allocations and interim calculations and include additional guidance in order to reduce complexity in accounting for income taxes. The Company is currently evaluating the effects of the standard on its financial statements. The guidance is effective for fiscal years beginning after December 15, 2021. Early adoption is permitted.

PREMIUMS EARNED

PREMIUMS EARNED	9 Months Ended
	Sep. 30, 2021
Insurance [Abstract]
PREMIUMS EARNED	PREMIUMS EARNED Premium revenue includes direct policy premiums collected directly from members and from the Centers for Medicare & Medicaid Services ("CMS") as part of the Advanced Premium Tax Credit Program ("APTC") and Medicare Advantage programs, along with assumed premiums from the Company's reinsurance agreements. Premium revenue is adjusted for the estimated impact of the risk adjustment program required by CMS. Total premiums earned includes the effect of reinsurance premiums ceded as part of the Company's reinsurance agreements. Refer to Note 4 - Reinsurance for more information. Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct policy premiums $ 895,407 $ 584,811 $ 2,554,296 $ 1,737,267 Assumed premiums 3,830 — 9,426 — Direct and assumed premiums 899,237 584,811 2,563,722 1,737,267 Risk adjustment (225,777) (170,306) (556,236) (504,774) Premiums before ceded reinsurance 673,460 414,505 2,007,486 1,232,493 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Total premiums earned $ 441,743 $ 99,145 $ 1,338,439 $ 298,120 The following table summarizes the amounts of direct policy premiums received directly from CMS as part of APTC and Medicare Advantage for the three and nine months ended September 30, 2021 and 2020: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) APTC $ 668,647 $ 348,229 $ 1,812,335 $ 1,025,021 Medicare Advantage 9,969 4,477 29,472 12,622 Total paid by CMS $ 678,616 $ 352,706 $ 1,841,807 $ 1,037,643 REINSURANCE The Company has entered into quota share reinsurance agreements with reinsurers under which the reinsurer assumes an agreed percentage of the underlying policies being reinsured and shares all premiums and incurred claims accordingly. As of April 1, 2021, the Company is party to reinsurance agreements with one reinsurer. Under the 2021 agreements, all premiums and claims ceded under the Company's quota share arrangements are shared proportionally with the reinsurers. Under the 2020 agreements, premiums and claims ceded are shared proportionally with the reinsurers, up to a limit specified in each agreement. The limit was removed from the 2021 agreements effective as of January 1, 2021. As part of the 2020 and 2021 agreements, the Company receives ceding commissions, which are calculated based on a percentage of ceded premiums, and experience refunds (resulting from actual claims experience being lower than a specified threshold). The composition of total reinsurance premiums ceded and reinsurance premiums assumed, which are included as components of total premiums earned in the consolidated statement of operations, is as follows: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Reinsurance premiums ceded, gross $ (220,472) $ (338,685) $ (724,512) $ (1,002,822) Experience refunds (11,245) 23,325 55,465 68,449 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Reinsurance premiums assumed 3,830 — 9,426 — Total reinsurance premiums (ceded) and assumed $ (227,887) $ (315,360) $ (659,621) $ (934,373) The Company records claims expense net of reinsurance recoveries. The following table reconciles the total claims expense to the net claims expense as presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct claims incurred $ 668,966 $ 370,329 $ 1,725,089 $ 961,946 Ceded reinsurance claims (220,894) (284,937) (593,175) (736,824) Assumed reinsurance claims 5,504 — 9,589 (2) Total claims incurred, net $ 453,576 $ 85,392 $ 1,141,503 $ 225,120 The Company records selling, general and administrative expenses net of ceding commissions. The following table reconciles total other insurance costs to the amount presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Other insurance costs, gross $ 129,516 $ 70,283 $ 343,915 $ 216,106 Ceding commissions (18,214) (31,609) (57,986) (96,884) Other insurance costs, net $ 111,302 $ 38,674 $ 285,929 $ 119,222 The Company records reinsurance recoverables as “balances due from reinsurance programs” within current assets on its consolidated balance sheets. The composition of the reinsurance recoverables balance is as follows: September 30, 2021 December 31, 2020 (in thousands) Ceded reinsurance claim recoverables $ 378,921 $ 435,331 Reinsurance ceding commissions 27,559 41,586 Experience refunds on reinsurance agreements 7,309 102,476 Balances due from reinsurance programs $ 413,789 $ 579,393 The Company regularly evaluates the financial condition of its reinsurers to minimize exposure to significant losses. A key credit quality indicator for reinsurance is the financial strength ratings issued by the credit rating agencies, which provide an independent opinion of a reinsurer’s ability to meet ongoing obligations to policyholders. As of September 30, 2021, the Company's reinsurer has financial strength ratings of AA- (S&P and Fitch) and Aa3 (Moody's).

REINSURANCE

REINSURANCE	9 Months Ended
	Sep. 30, 2021
Insurance [Abstract]
REINSURANCE	PREMIUMS EARNED Premium revenue includes direct policy premiums collected directly from members and from the Centers for Medicare & Medicaid Services ("CMS") as part of the Advanced Premium Tax Credit Program ("APTC") and Medicare Advantage programs, along with assumed premiums from the Company's reinsurance agreements. Premium revenue is adjusted for the estimated impact of the risk adjustment program required by CMS. Total premiums earned includes the effect of reinsurance premiums ceded as part of the Company's reinsurance agreements. Refer to Note 4 - Reinsurance for more information. Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct policy premiums $ 895,407 $ 584,811 $ 2,554,296 $ 1,737,267 Assumed premiums 3,830 — 9,426 — Direct and assumed premiums 899,237 584,811 2,563,722 1,737,267 Risk adjustment (225,777) (170,306) (556,236) (504,774) Premiums before ceded reinsurance 673,460 414,505 2,007,486 1,232,493 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Total premiums earned $ 441,743 $ 99,145 $ 1,338,439 $ 298,120 The following table summarizes the amounts of direct policy premiums received directly from CMS as part of APTC and Medicare Advantage for the three and nine months ended September 30, 2021 and 2020: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) APTC $ 668,647 $ 348,229 $ 1,812,335 $ 1,025,021 Medicare Advantage 9,969 4,477 29,472 12,622 Total paid by CMS $ 678,616 $ 352,706 $ 1,841,807 $ 1,037,643 REINSURANCE The Company has entered into quota share reinsurance agreements with reinsurers under which the reinsurer assumes an agreed percentage of the underlying policies being reinsured and shares all premiums and incurred claims accordingly. As of April 1, 2021, the Company is party to reinsurance agreements with one reinsurer. Under the 2021 agreements, all premiums and claims ceded under the Company's quota share arrangements are shared proportionally with the reinsurers. Under the 2020 agreements, premiums and claims ceded are shared proportionally with the reinsurers, up to a limit specified in each agreement. The limit was removed from the 2021 agreements effective as of January 1, 2021. As part of the 2020 and 2021 agreements, the Company receives ceding commissions, which are calculated based on a percentage of ceded premiums, and experience refunds (resulting from actual claims experience being lower than a specified threshold). The composition of total reinsurance premiums ceded and reinsurance premiums assumed, which are included as components of total premiums earned in the consolidated statement of operations, is as follows: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Reinsurance premiums ceded, gross $ (220,472) $ (338,685) $ (724,512) $ (1,002,822) Experience refunds (11,245) 23,325 55,465 68,449 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Reinsurance premiums assumed 3,830 — 9,426 — Total reinsurance premiums (ceded) and assumed $ (227,887) $ (315,360) $ (659,621) $ (934,373) The Company records claims expense net of reinsurance recoveries. The following table reconciles the total claims expense to the net claims expense as presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct claims incurred $ 668,966 $ 370,329 $ 1,725,089 $ 961,946 Ceded reinsurance claims (220,894) (284,937) (593,175) (736,824) Assumed reinsurance claims 5,504 — 9,589 (2) Total claims incurred, net $ 453,576 $ 85,392 $ 1,141,503 $ 225,120 The Company records selling, general and administrative expenses net of ceding commissions. The following table reconciles total other insurance costs to the amount presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Other insurance costs, gross $ 129,516 $ 70,283 $ 343,915 $ 216,106 Ceding commissions (18,214) (31,609) (57,986) (96,884) Other insurance costs, net $ 111,302 $ 38,674 $ 285,929 $ 119,222 The Company records reinsurance recoverables as “balances due from reinsurance programs” within current assets on its consolidated balance sheets. The composition of the reinsurance recoverables balance is as follows: September 30, 2021 December 31, 2020 (in thousands) Ceded reinsurance claim recoverables $ 378,921 $ 435,331 Reinsurance ceding commissions 27,559 41,586 Experience refunds on reinsurance agreements 7,309 102,476 Balances due from reinsurance programs $ 413,789 $ 579,393 The Company regularly evaluates the financial condition of its reinsurers to minimize exposure to significant losses. A key credit quality indicator for reinsurance is the financial strength ratings issued by the credit rating agencies, which provide an independent opinion of a reinsurer’s ability to meet ongoing obligations to policyholders. As of September 30, 2021, the Company's reinsurer has financial strength ratings of AA- (S&P and Fitch) and Aa3 (Moody's).

RESTRICTED CASH AND RESTRICTED

RESTRICTED CASH AND RESTRICTED DEPOSITS	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
RESTRICTED CASH AND RESTRICTED DEPOSITS	RESTRICTED CASH AND RESTRICTED DEPOSITS The Company maintains cash, cash equivalents and investments on deposit or pledged primarily to various state agencies in connection with its insurance licensure. Deposited and pledged cash equivalents and investments are recorded at fair value. States require that deposited investments remain on deposit indefinitely and, therefore, the Company classifies these restricted deposits as long-term regardless of the contractual maturity date of the securities held. The restricted cash and cash equivalents and restricted investments presented below are included in “restricted deposits” in the accompanying consolidated balance sheets. September 30, 2021 December 31, 2020 (in thousands) Restricted cash and cash equivalents $ 21,243 $ 16,779 Restricted investments 6,514 9,699 Restricted Deposits $ 27,757 $ 26,478

INVESTMENTS

INVESTMENTS	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	INVESTMENTS The following tables provide summaries of the Company's investments by major security type at September 30, 2021 and December 31, 2020: September 30, 2021 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) U.S. treasury and agency securities $ 859,612 $ 246 $ (105) $ 859,753 Corporate notes 466,189 114 (244) 466,059 Certificate of deposit 26,623 — — 26,623 Commercial paper 35,538 — — 35,538 Municipalities 37,285 1 (32) 37,254 Total $ 1,425,247 $ 361 $ (381) $ 1,425,227 December 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) U.S. treasury and agency securities $ 523,809 $ 562 $ (2) $ 524,369 Corporate notes 159,461 262 (58) 159,665 Commercial paper 7,043 — — 7,043 Certificate of deposit 1,050 — — 1,050 Total $ 691,363 $ 824 $ (60) $ 692,127 There are no available-for-sale securities that have been in a continuous unrealized loss position for longer than twelve months. At September 30, 2021 and December 31, 2020, the available-for-sale securities that mature within one year or less in a gross unrealized loss position are as follows: September 30, 2021 Number of Securities Fair Value Gross (in thousands) Investments twelve months or less: U.S. treasury and agency securities 60 $ 327,422 $ — Corporate notes 150 185,724 (42) Municipalities 38 $ 13,268 (5) Total 248 $ 526,414 $ (47) December 31, 2020 Number of Securities Fair Value Gross (in thousands) Investments twelve months or less: U.S. treasury and agency securities 51 $ 339,014 $ (2) Corporate notes 40 19,280 (3) Total 91 $ 358,294 $ (5) At September 30, 2021 and December 31, 2020, the available-for-sale securities that mature over twelve months or more in a gross unrealized loss position are as follows: September 30, 2021 Number of Securities Fair Value Gross (in thousands) Investments over twelve months: U.S. treasury and agency securities 47 $ 532,331 $ (105) Corporate notes 215 280,336 (202) Municipalities 57 $ 23,986 $ (27) Total 319 $ 836,653 $ (334) December 31, 2020 Number of Securities Fair Value Gross (in thousands) Investments over twelve months: Corporate notes 189 140,384 (55) Total 189 $ 140,384 $ (55) Net investment income was attributable to the following: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Interest income $ 3,125 $ 2,018 $ 7,054 $ 6,500 Investment discount amortization net of premium accretion (2,458) (1,035) (5,520) (1,511) Net realized gain (loss) 21 489 271 936 Total $ 688 $ 1,472 $ 1,805 $ 5,925 The Company regularly evaluates its investments in debt securities to determine if a decline in value is other-than-temporary. When evaluating these declines, the Company assesses the severity of the loss relative to its original cost and the time that the market value has been less than its original cost, and considers the Company’s intent to retain the investments for a long enough period to allow for a sufficient market recovery. If a decline in the value of a debt security is considered other-than-temporary, the Company reduces the investment through a charge to the consolidated statement of operations. No adjustments were necessary during the periods presented.

FAIR VALUE

FAIR VALUE	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUE Fair value represents the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that is determined based on assumptions that market participants would use in pricing an asset or a liability. Assets and liabilities recorded at fair values are measured in accordance with a three-tier fair value hierarchy based on the observability of the inputs available in the market used to measure fair value: • Pricing Level 1 - Quoted prices in active markets for identical assets or liabilities. • Pricing Level 2 - Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. • Pricing Level 3 - Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the assets or liability. Assets and liabilities measured at fair value on recurring basis are as follows: September 30, 2021 (Level 1) (Level 2) (Level 3) Total Fair Value Measurement (in thousands) Investments U.S. treasury and agency securities $ — $ 859,753 $ — $ 859,753 Corporate notes — 466,059 — 466,059 Commercial paper — 35,538 — 35,538 Certificate of deposit — 26,623 — 26,623 Municipalities — 37,254 — 37,254 Total $ — $ 1,425,227 $ — $ 1,425,227 December 31, 2020 (Level 1) (Level 2) (Level 3) Total Fair Value Measurement (in thousands) Investments U.S. treasury and agency securities $ — $ 524,369 $ — $ 524,369 Corporate notes — 159,665 — 159,665 Commercial paper — 7,043 — 7,043 Certificate of deposit — 1,050 — 1,050 Total $ — $ 692,127 $ — $ 692,127 Warrant liabilities $ — $ — $ 15,005 $ 15,005 The Company classifies investments within Level 2 because the Company uses quoted market prices or alternative pricing sources that are based on market observable inputs to determine their fair value. The carrying values of restricted deposits reported on the consolidated balance sheet but not listed in the table above approximate their fair value. Cash and cash equivalents are carried at cost, which approximates fair value. The Company classified warrant liabilities within Level 3 value hierarchy because the liability was based on present value calculations and external valuation models whose inputs include market interest rates, estimated operational capitalization rates, and volatilities. Fair value is determined using an option pricing model. The table below presents changes in the fair value of the Company’s Level 3 warrant liabilities at September 30, 2021 and December 31, 2020 as follows: September 30, 2021 December 31, 2020 (in thousands) Beginning balance $ 15,005 $ 8,819 Vesting of warrants — 392 Change in fair value 13,243 4,709 Preferred Stock Series A11 call options issued — 13,488 Preferred Stock Series A11 call options exercised (70) (12,403) Preferred Stock Series AA, A8, and A9 exercised (28,178) — Ending balance $ — $ 15,005 As of December 31, 2020, the Company classified long-term debt within Level 3 value hierarchy because the fair value of the liability was based upon a market approach with various unobservable inputs such as market price quotations, discount margins, market spreads applied, the terms and liquidity of the instrument, the financial condition, operating results and credit ratings of the issuer or underlying company, the quoted market price of publicly traded securities with similar duration and yield, time value, yield curve, default rates, as well as other measurements. As of December 31, 2020, the fair value approximated the carrying value as the debt was issued near year end and there was little volatility in interest rates. The long-term debt was paid in full in March 2021 (see Note 9 - Debt and Warrants).

BENEFITS PAYABLE

BENEFITS PAYABLE	9 Months Ended
	Sep. 30, 2021
Insurance [Abstract]
BENEFITS PAYABLE	BENEFITS PAYABLE Reserves for medical claims expenses are estimated using actuarial assumptions and recorded as a benefits payable liability on the consolidated balance sheet. The assumptions for the estimates and for establishing the resulting liability are reviewed, and any adjustments to reserves are reflected in the consolidated statement of operations in the period in which the estimates are updated. The following table provides a rollforward of the Company’s beginning and ending benefits payable and claims adjustment expenses ("CAE") payable balances for the nine months ended September 30, 2021 and 2020: As of September 30, 2021 Benefits Payable Unallocated Claims Total (in thousands) Benefits payable, beginning of the period $ 311,914 $ 5,509 $ 317,423 Less: Reinsurance recoverable 132,658 — 132,658 Benefits payable, beginning of the period, net $ 179,256 $ 5,509 $ 184,765 Claims incurred and CAE Current year $ 1,151,734 $ 43,239 $ 1,194,973 Prior years (10,231) — (10,231) Total claims incurred and CAE, net $ 1,141,503 $ 43,239 $ 1,184,742 Claims paid and CAE Current year $ 885,043 $ 34,428 $ 919,471 Prior years 100,091 5,509 105,600 Total claims and CAE paid, net $ 985,134 $ 39,937 $ 1,025,071 Benefits and CAE payable, end of period, net $ 335,625 $ 8,811 $ 344,436 Add: Reinsurance recoverable 161,699 — 161,699 Benefits and CAE payable, end of period $ 497,324 $ 8,811 $ 506,135 As of September 30, 2020 Benefits Payable Unallocated Claims Total (in thousands) Benefits payable, beginning of the period $ 156,557 $ 3,009 $ 159,566 Less: Reinsurance recoverable 76,183 — 76,183 Benefits payable, beginning of the period, net $ 80,374 $ 3,009 $ 83,383 Claims incurred and CAE Current year $ 232,686 $ 33,262 $ 265,948 Prior years (7,566) — (7,566) Total claims incurred and CAE, net $ 225,120 $ 33,262 $ 258,382 Claims paid and CAE Current year $ 189,281 $ 28,410 $ 217,691 Prior years 30,835 3,009 33,844 Total claims and CAE paid, net $ 220,116 $ 31,419 $ 251,535 Benefits and CAE payable, end of period, net $ 85,378 $ 4,852 $ 90,230 Add: Reinsurance recoverable 191,134 — 191,134 Benefits and CAE payable, end of period $ 276,512 $ 4,852 $ 281,364

DEBT AND WARRANTS

DEBT AND WARRANTS	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
DEBT AND WARRANTS	DEBT AND WARRANTS Long-Term Debt On October 30, 2020, the Company entered into a credit agreement (“Facility Agreement”) with HPS Investment Partners, LLC (“HPSIP”) whereby HPSIP agreed to provide a $150.0 million first lien term loan (“Term Loan”). The Term Loan had a variable interest rate equal to LIBOR plus 11.75%, per annum, which equated to 12.75% per annum during the period, and a maturity date of October 30, 2024, subject to certain conditions. On March 5, 2021, the Company used proceeds from its recently completed IPO to repay the outstanding balance of $153.2 million on its Term Loan, which included $3.2 million of paid-in-kind interest. A loss on debt extinguishment of $20.2 million was recognized, which consisted of $13.0 million in prepayment penalties and $7.2 million in unamortized debt discount and debt issuance costs. Revolving Credit Facility On February 21, 2021, the Company entered into a senior secured credit agreement (the “Revolving Credit Facility”), with certain lenders party thereto from time to time (the “Lenders”), and Wells Fargo Bank, National Association, as administrative agent, for a revolving loan credit facility in the aggregate principal amount of $200.0 million. The Revolving Credit Facility is guaranteed by Oscar Management Corporation, a wholly owned subsidiary of the Company, and all of the Company's future direct and indirect subsidiaries (subject to certain permitted exceptions, including exceptions guarantees that would require material governmental consents or in respect of a joint venture) (the "Guarantors"). The Revolving Credit Facility is secured by substantially all of the Company’s and the Guarantors' assets (subject to certain exceptions). Proceeds are to be used solely for general corporate purposes of the Company. The Company is permitted to increase commitments under the Revolving Credit Facility by an aggregate amount not to exceed $50.0 million, subject to certain conditions. The Revolving Credit Facility matures on February 21, 2024. Under the terms of the Revolving Credit Facility, borrowings under the Revolving Credit Facility bear interest at a rate equal to, at the Company's option, either (a) a rate per annum equal to an Adjusted LIBO Rate, plus an applicable margin of 4.50% (Adjusted London Interbank Offered Rate, or LIBO rate, is calculated based on one-, three- or six-month LIBO rates, or such other period as agreed by all relevant Lenders, which is determined by reference to ICE Benchmark Administration Limited, but not less than 1.00%), or (b) a rate per annum equal to the Alternate Base Rate, as defined in the Revolving Credit Facility, plus the applicable margin of 3.50% (the Alternate Base Rate is equal to the highest of (i) the prime rate, (ii) the federal funds effective rate plus 0.50%, and (iii) the Adjusted LIBO Rate based on a one-month interest period, plus 1.00%). The Revolving Credit Facility also includes a commitment fee of 0.50% for available but undrawn amounts and other administrative fees that are payable quarterly. It also includes LIBO rate replacement provisions in the event LIBO rate becomes unavailable during the term of this facility. The Revolving Credit Facility is available until February 2024, provided the Company is in compliance with all covenants. Financial covenant requirements include maintaining minimum thresholds related to direct policy premiums and liquidity and a maximum combined ratio. As of September 30, 2021, there were no outstanding borrowings under the Revolving Credit Facility. Warrants and Call Options In prior years, the Company issued several rounds of warrants to purchase preferred stock. Since the Company’s convertible preferred stock was classified outside of permanent equity, the warrants were accounted for as liabilities using the fair market value on the issuance date, with remeasurement required at each reporting period. During the nine months ended September 30, 2021 and 2020, a gain (loss) on the fair value of warrant liabilities of $(12.9) million and $0.5 million, respectively, was recognized in general and administrative expenses in the consolidated statement of operations as a result of the changes in fair value of the warrant liabilities. The following table presents relevant information regarding outstanding warrants and call options: Warrant Type Issue Date Warrants Issued Issue Price Maximum No. of Preferred Stock Issuable Warrants Outstanding as of 12/31/20 Warrants Outstanding as of 9/30/21 Series AA Warrant 2013 629,152 $ 0.56 629,152 629,152 — Series A8 Warrant 2017 166,666 $ 6.75 166,666 166,666 — Series A9 Warrant 2018 416,666 $ 7.13 416,666 416,666 — Series A11 Call Options 2020 4,143,028 $ 6.02 4,143,028 12,732 — 1,225,216

CONVERTIBLE PREFERRED STOCK

CONVERTIBLE PREFERRED STOCK	9 Months Ended
	Sep. 30, 2021
Temporary Equity Disclosure [Abstract]
CONVERTIBLE PREFERRED STOCK	CONVERTIBLE PREFERRED STOCK In prior years, the Company issued several series of convertible preferred stock, collectively referred to as "Preferred Stock," that have been classified outside of stockholders' equity (deficit) on the consolidated balance sheet because the holders of such shares had liquidation rights that, in certain situations, were not solely within the control of the Company. In connection with the IPO, all convertible preferred stock outstanding as of December 31, 2020 were converted into shares of Series A and Series B common stock. Refer to Note 11 - Stockholders' Equity for more information. The table below presents relevant information relating to convertible preferred stock for the periods presented: December 31, 2020 September 30, 2021 Preferred Stock Preferred Stock Outstanding (pre-split) Preferred Stock Converted to Common Stock (Series A/B) (pre-split) Preferred Stock Outstanding A 41,913,800 (41,913,800) — A1 1,371,010 (1,371,010) — AA 22,379,980 (22,379,980) — AAA 36,109,790 (36,109,790) — A4 23,142,080 (23,142,080) — A5 29,189,760 (29,189,760) — A6 29,942,474 (29,942,474) — A7 6,265,845 (6,265,845) — A8 56,434,363 (56,434,363) — A9 23,177,793 (23,177,793) — AA-9 11,820,502 (11,820,502) — A10 53,877,952 (53,877,952) — A11 49,678,169 (49,678,169) — A12 15,600,784 (15,600,784) — Total 400,904,302 (400,904,302) —

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Initial Public Offering As described in Note 1 - Organization, in March 2021 the Company completed its IPO of 36,391,946 shares of Class A common stock at a par value of $0.00001 and a public offering price of $39.00 per share. The Company received aggregate net proceeds of $1.3 billion after deducting underwriting discounts and commissions of $71.0 million. The Company used a portion of the net proceeds of the IPO to repay in full outstanding borrowings, including fees and expenses, under the Term Loan Facility. Refer to Note 9 - Debt and Warrants. Reclassification and Stock Split Conversion of Preferred Stock and Series B Common Stock to Series A Common Stock In accordance with the terms and provisions of the Company’s Thirteenth Amended and Restated Certificate of Incorporation (the “Prior Certificate of Incorporation”), which was in effect immediately prior to the filing of the Amended and Restated Certificate of Incorporation, the holders of 402,192,500 shares (pre-split) of the Company’s convertible preferred stock effected a conversion of all shares of convertible preferred stock to 403,261,643 shares (pre-split) of Series A common stock, $0.00001 par value per share (the “Series A common stock”) (the “Preferred Stock Conversion”), and the holders of 9,360,800 shares (pre-split) of the Company’s Series B common stock, $0.00001 par value per share (the “Series B common stock”), effected a conversion of such shares of Series B common stock to 9,360,800 shares (pre-split) of the Company’s Series A common stock (the “Series B Conversion”), in each case effective as of the pricing of the IPO on March 2, 2021. Authorization of New Class of Shares and Conversion of Series A Common Stock and Stock Split In connection with the IPO, on March 3, 2021, the Company filed its Amended and Restated Certificate of Incorporation which, among other things, provides for: • the authorization of 825,000,000 shares of Class A common stock, 82,500,000 shares of Class B common stock, and 82,500,000 shares of preferred stock; • the reclassification of each share of Series A common stock (other than shares of Series A common stock held by Thrive Capital Partners II, L.P., Thrive Capital Partners III, L.P., Thrive Capital Partners V, L.P., Thrive Capital Partners VI Growth, L.P., Claremount TW, L.P., Claremount VI Associates, L.P. and Claremount V Associates, L.P. (the “Thrive Series A common stock”)) issued and outstanding or held in treasury immediately prior to the filing of the Amended and Restated Certificate of Incorporation into one share of Class A common stock (the “Class A Reclassification”); • the reclassification of each share of Series B common stock issued and outstanding or held in treasury immediately prior to the filing of the Amended and Restated Certificate of Incorporation and each share of Thrive Series A common stock into one share of Class B common stock (the “Class B Reclassification” and, together with the Class A Reclassification, the “Reclassification”); • the reclassification of each three shares of Class A common stock issued and outstanding or held in treasury immediately following the Class A Reclassification into one validly issued, fully paid and non-assessable share of Class A common stock (the “Class A Stock Split”); and • the reclassification of each three shares of Class B common stock issued and outstanding or held in treasury immediately following the Class B Reclassification into one validly issued, fully paid and non-assessable share of Class B common stock (the “Class B Stock Split” and, together with the Class A Stock Split, the “Stock Split”). No fractional shares of Class A common stock or Class B Common Stock were delivered as a result of the Stock Split. Summary of IPO Share Transactions As a result of the IPO, the Preferred Stock Conversion, the Series B Conversion, the Reclassification, and the Stock Split described above, the following activity occurred: • 402,192,500 shares (pre-split) of convertible preferred stock were converted into 403,261,643 shares (pre-split) of Series A common stock; • 9,360,800 shares (pre-split) of Series B common stock were converted into 9,360,800 shares (pre-split) of Series A common stock; • 398,283,107 shares (pre-split) of Series A common stock were reclassified as 398,283,107 shares (pre-split) of Class A common stock; • 60,127,163 shares (pre-split) of Series B Common Stock were reclassified as 60,127,163 shares (pre-split) of Class B common stock; • 45,879,623 shares (pre-split) of Series A common stock were reclassified as 45,879,623 shares (pre-split) of Class B common stock; • 398,283,107 shares (pre-split) of Class A common stock were reclassified as 132,760,639 shares (post-split) of Class A common stock; • 106,006,786 shares (pre-split) of Class B common stock were reclassified as 35,335,579 shares (post-split) of Class B common stock; • 219,772 shares (post-split) of Class B common stock converted to 219,772 shares (post-split) of Class A Common Stock in connection with a secondary sale in the IPO; and • the Company issued 36,391,946 shares (post-split) of Class A common stock at a par value of $0.00001 and a public offering price of $39.00 per share. Common Stock The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting, conversion, and transfer rights. Voting Rights Holders of the Company’s Class A common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders, and holders of the Company’s Class B common stock are entitled to 20 votes for each share held on all matters submitted to a vote of stockholders. The holders of the Company’s Class A common stock and Class B common stock will vote together as a single class, unless otherwise required by law or under the Amended and Restated Certificate of Incorporation. Conversion and Transfer Each outstanding share of Class B common stock is convertible at any time at the option of the holder into one share of Class A common stock. Each share of Class B common stock will convert automatically into one share of Class A Common Stock upon any transfer, except for certain permitted transfers described in the Amended and Restated Certificate of Incorporation. All outstanding shares of Class B common stock will automatically convert into shares of Class A common stock on a one-for-one basis upon the date that is the earlier of (i) the transfer of Class B common stock to a person or entity that is not in the transferor’s permitted ownership group, as described in the Amended and Restated Certificate of Incorporation, (ii) March 2, 2028, or (iii) upon the occurrence of certain other events as described in the Amended and Restated Certificate of Incorporation.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION 2012 Incentive Award Plan Prior to the IPO, the Company maintained the 2012 Stock Plan (the “2012 Plan”), which provided for the grant of incentive stock options ("ISOs"), non-qualified stock options ("NSOs"), common stock of the Company, stock payments and restricted stock units ("RSUs"). The 2012 Plan was initially adopted on December 6, 2012 and most recently amended and restated in October 2020. The 2012 Plan was terminated upon the effectiveness of the 2021 Incentive Award Plan in March 2021, and no further awards will be made under the 2012 Plan. 2021 Incentive Award Plan In March 2021, the Company’s board of directors adopted the 2021 Incentive Award Plan (the “2021 Plan”), which provides for the grant of NSOs, ISOs, stock appreciation rights (“SARs”), restricted stock, RSUs, performance awards, dividend equivalents and other stock or cash awards to employees, consultants and non-employee directors. Stock-Based Compensation Expense The following table summarizes the stock-based compensation expense for the three and nine months ended September 30, 2021 and 2020, which is included within the line items specified below in the consolidated statements of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Other insurance costs $ 10,122 $ 3,785 $ 28,988 $ 11,144 General and administrative expenses 10,518 3,502 29,040 10,840 Total stock-based compensation expense $ 20,640 $ 7,287 $ 58,028 $ 21,984 Stock Options Stock options granted under the 2012 Plan and 2021 Plan include ISOs and NSOs, generally have a maximum contractual term of 10 years and typically vest over a four-year period. The following table summarizes the stock option award activity under the 2012 Plan and 2021 Plan for the nine months ended September 30, 2021: September 30, 2021 Number of Options Weighted Average Exercise Price Weighted Average Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Options Outstanding - December 31, 2020 41,115,486 $ 9.19 7.59 $ 279,477 Options granted 2,477,088 $ 22.49 Options exercised (5,990,310) $ 7.36 $ 106,326 Options canceled (2,417,301) $ 18.12 Options Outstanding - September 30, 2021 35,184,963 $ 10.21 7.17 $ 265,197 Options Exercisable at September 30, 2021 21,844,883 $ 8.37 6.23 $ 197,406 Determination of Fair Value of Stock Options The fair value of stock option awards granted is estimated on the grant date using the Black-Scholes option pricing model. The weighted average grant date fair value of options granted during the nine months ended September 30, 2021 was $8.98. The table below summarizes the assumptions used: September 30, 2021 Term in years 6.03 years Dividend rate — % Risk free rate of return 0.86 % Volatility 41.63 % Compensation Expense – Stock Options During the three months ended September 30, 2021 and 2020, the Company recorded compensation expense of $7.8 million and $7.3 million, respectively. During the nine months ended September 30, 2021 and 2020, the Company recorded compensation expense of $30.5 million and $22.0 million, respectively. As of September 30, 2021, the amount of unrecognized compensation expense for stock options is $62.4 million, which is expected to be recognized over a weighted-average period of 2.7 years. Restricted Stock Units RSUs represent the right to receive shares of the Company’s Class A common stock at a specified date in the future and typically have a vesting period of one The following table summarizes RSU award activity for the nine months ended September 30, 2021: RSUs Number of Shares Weighted Average Grant Date Fair Value Outstanding RSUs at December 31, 2020 1,555,666 $ 15.82 RSUs granted 7,103,359 $ 17.82 RSUs vested (246,907) $ 23.31 RSUs canceled (165,017) $ 21.71 Outstanding RSUs at September 30, 2021 8,247,101 $ 17.20 Determination of Fair Value of RSUs The fair value of RSUs granted is determined on the grant date based on the fair value of the Company's common stock. Compensation Expense – RSUs During the three and nine months ended September 30, 2021, the Company recorded compensation expense of $7.2 million and $15.1 million, respectively. As of September 30, 2021, the amount of unrecognized compensation expense for RSUs is $132.0 million, which is expected to be recognized over a weighted-average period of 3.0 years. Performance-based Restricted Stock Units Performance-based restricted stock units ("PSUs") represent the right to receive shares of the Company’s Class A common stock at a specified date in the future based on pre-determined performance and service conditions and typically have a vesting period of one The following table summarizes PSU award activity for the nine months ended September 30, 2021: PSU Number of Shares Weighted Average Grant Date Fair Value Outstanding PSUs at December 31, 2020 — $ — PSUs granted 7,082,432 $ 14.37 PSUs canceled — $ — Outstanding PSUs at September 30, 2021 7,082,432 $ 14.37 Compensation Expense – PSUs During the three and nine months ended September 30, 2021, the Company recorded compensation expense of $5.7 million and $12.5 million, respectively. As of September 30, 2021, the amount of unrecognized compensation expense for PSUs is $89.2 million, which is expected to be recognized over a weighted-average period of 3.9 years.

EARNINGS (LOSS) PER SHARE

EARNINGS (LOSS) PER SHARE	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
EARNINGS (LOSS) PER SHARE	EARNINGS (LOSS) PER SHARE Earnings (loss) per share ("EPS") is calculated using the two-class method, which is an earnings allocation model that treats participating securities as having rights to earnings that otherwise would have been available to common stockholders. Under the two-class method, earnings for the period are required to be allocated between common stock and participating securities based upon their respective rights to receive distributed and undistributed earnings. For EPS computation purposes, the Company's Class A and Class B common stock are considered one single class of common stock because both classes have the same dividend and liquidation rights. The following table presents the computation of basic and diluted earnings per share: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands, except share and per share data) Numerator : Net loss attributable to common stockholders $ (212,745) $ (79,132) $ (373,184) $ (216,955) Denominator : Weighted average shares of common stock outstanding, basic and diluted 208,159,343 29,042,932 168,585,157 28,941,215 Net loss per share, basic and diluted $ (1.02) $ (2.72) $ (2.21) $ (7.50) In periods when the Company is in a net loss position, dilutive securities are excluded from the computation of diluted earnings per share because their inclusion would have an anti-dilutive effect. Thus, basic net loss per share is the same as diluted net loss per share.

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
VARIABLE INTEREST ENTITIES	VARIABLE INTEREST ENTITIESIn the normal course of business, the Company enters into business arrangements with integrated health systems, which include multiple hospitals, health care centers, large independent practice associations, physicians and ancillary providers licensed to provide health care services in the states of Ohio and New York, and several medical professional corporations (collectively, the "Professional Corporations") that employ health care providers to deliver telemedical healthcare services to its covered member population in various states. The Company evaluated its involvement with these entities and considered whether it has (i) the power to direct the activities of the VIE that most significantly impact the economic performance of the VIE and (ii) the obligation to absorb losses of, or the right to receive benefits from, the VIE that could be potentially significant to the VIE. The Company has determined that consolidation was required because these entities are deemed VIEs and the Company is considered to be the primary beneficiary of these entities. Integrated Health Systems The Company has arrangements with integrated health systems through its wholly-owned subsidiaries, Oscar Insurance Corporation of Ohio and Oscar Health Plan of New York, which are consolidated into the Company’s financial results pursuant to the guidance regarding Variable Interest Entities. For the Company’s arrangements with integrated health systems, the Company shares 50% of the underwriting risks through shared savings and 50% of net income. Payments to the healthcare networks are expensed and are included in claims incurred, net in the consolidated statement of operations. For the three and nine months ended September 30, 2021, the Company generated $4.5 million and $1.6 million, respectively of income through shared savings arrangements. The Company did not have any shared services arrangements with the integrated health systems during the three and nine months ended September 30, 2020. Professional Corporations The Company has a series of contractual relationships with several medical professional corporations and has determined it has a controlling financial interest in them because, as part of its arrangement, it has guaranteed their debt, and the equity at risk is insufficient to finance their activities without additional subordinated financial support from the Company. The following table presents the collective assets and liabilities of the professional corporations: September 30, 2021 December 31, 2020 (in thousands) Assets $ 2,240 $ 1,862 Liabilities $ 11,762 $ 7,589 The following table presents the collective revenues and operating expenses of the professional corporations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Revenues $ 3,402 $ 1,824 $ 9,189 $ 5,122 Operating expenses $ 4,119 $ 3,129 $ 12,768 $ 9,004

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES The Company is also currently involved in, and may in the future from time to time become involved in, legal proceedings and other claims in the ordinary course of its business, including class actions and suits brought by the Company’s members, providers, commercial counterparties, employees, and other parties relating to the Company’s business, including management and administration of health benefit plans and other services. Such matters can include various employment claims, disputes regarding reinsurance arrangements and class action lawsuits, or other claims relating to the performance of contractual and non-contractual obligations to providers, members, employer groups, and others, including, but not limited to, the alleged failure to properly pay in-network and out-of-network claims and challenges to the manner in which the Company processes claims, and claims alleging that the Company has engaged in unfair business practices. The Company records liabilities for its estimates of probable costs resulting from these matters where appropriate. Estimates of costs resulting from legal and regulatory matters involving the Company are inherently difficult to predict, particularly where the matters: involve indeterminate claims for monetary damages or may involve fines, penalties or punitive damages; present novel legal theories or represent a shift in regulatory policy; involve a large number of claimants or regulatory bodies; are in the early stages of the proceedings; or could result in a change in business practices. Accordingly, the Company is often unable to estimate the losses or ranges of losses for those matters where there is a reasonable possibility or it is probable that a loss may be incurred, the ultimate settlement of which could be material. Although it is not possible to accurately predict or determine the eventual outcomes of these items, the Company believes that there are no pending legal proceedings that, individually or in the aggregate, would have a material effect on its business, financial condition or operating results.

ORGANIZATION (Policies)

ORGANIZATION (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying interim condensed consolidated financial statements of the Company are unaudited. These interim unaudited condensed consolidated financial statements have been prepared in accordance with U.S. GAAP, and the applicable rules and regulations of the Securities and Exchange Commission ("SEC") for interim financial information. As such, these financial statements do not include all information and footnotes required by U.S. GAAP for complete financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the unaudited consolidated financial statements and accompanying notes. Significant estimates inherent in the preparation of the accompanying unaudited consolidated financial statements include healthcare costs incurred but not yet reported (“IBNR”), reinsurance, premium deficiency reserve (“PDR”), risk adjustment, stock-based compensation, premium receivable allowance and income taxes. Estimates are based on past experience and other considerations reasonable under the circumstances. Actual results may differ materially from these estimates. Additionally, the full extent to which the outbreak of COVID-19 could impact the Company’s business, results of operations and financial condition is still unknown and will depend on future developments, which are highly uncertain and cannot be predicted. However, the Company has made accounting estimates based on the facts and circumstances available as of the reporting date. The Company has not currently experienced significant negative impact to its operations, liquidity or capital resources as a result of the COVID-19 pandemic.
Accounting Pronouncements - Not Yet Adopted	Accounting Pronouncements - Not Yet Adopted In February 2016, the FASB issued ASU 2016- 02, Leases (Topic 842) . The ASU requires lessees to recognize a right-of-use asset and a lease liability for all leases with an initial term in excess of twelve months. The asset reflects the present value of unpaid lease payments coupled with initial direct costs, prepaid lease payments and lease incentives. The amount of the lease liability is calculated as the present value of unpaid lease payments. The Company is currently in the process of finalizing the key data inputs required to calculate the financial statement impact of the new guidance. The adoption of this guidance was deferred under the extended transition period provided to EGCs. The Company expects to adopt this guidance as of January 1, 2021 in its December 31, 2021 financial statements using the modified retrospective method of adoption. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326) . The ASU provides new guidance for estimating credit losses on certain types of financial instruments by introducing an approach based on expected losses. The Company is currently in the implementation phase of adoption and is evaluating the effects of the standard on its financial statements. The adoption of this guidance was deferred under the extended transition period provided to EGCs. The Company expects to adopt this guidance as of January 1, 2021 in its December 31, 2021 financial statements using the modified retrospective method of adoption. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes . The amendments in this ASU simplify the accounting for income taxes by removing certain exceptions for investments, intra-period allocations and interim calculations and include additional guidance in order to reduce complexity in accounting for income taxes. The Company is currently evaluating the effects of the standard on its financial statements. The guidance is effective for fiscal years beginning after December 15, 2021. Early adoption is permitted.

PREMIUMS EARNED (Tables)

PREMIUMS EARNED (Tables)	9 Months Ended
	Sep. 30, 2021
Insurance [Abstract]
Schedule of premiums earned	Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct policy premiums $ 895,407 $ 584,811 $ 2,554,296 $ 1,737,267 Assumed premiums 3,830 — 9,426 — Direct and assumed premiums 899,237 584,811 2,563,722 1,737,267 Risk adjustment (225,777) (170,306) (556,236) (504,774) Premiums before ceded reinsurance 673,460 414,505 2,007,486 1,232,493 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Total premiums earned $ 441,743 $ 99,145 $ 1,338,439 $ 298,120 The following table summarizes the amounts of direct policy premiums received directly from CMS as part of APTC and Medicare Advantage for the three and nine months ended September 30, 2021 and 2020: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) APTC $ 668,647 $ 348,229 $ 1,812,335 $ 1,025,021 Medicare Advantage 9,969 4,477 29,472 12,622 Total paid by CMS $ 678,616 $ 352,706 $ 1,841,807 $ 1,037,643 The composition of total reinsurance premiums ceded and reinsurance premiums assumed, which are included as components of total premiums earned in the consolidated statement of operations, is as follows: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Reinsurance premiums ceded, gross $ (220,472) $ (338,685) $ (724,512) $ (1,002,822) Experience refunds (11,245) 23,325 55,465 68,449 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Reinsurance premiums assumed 3,830 — 9,426 — Total reinsurance premiums (ceded) and assumed $ (227,887) $ (315,360) $ (659,621) $ (934,373) The Company records claims expense net of reinsurance recoveries. The following table reconciles the total claims expense to the net claims expense as presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct claims incurred $ 668,966 $ 370,329 $ 1,725,089 $ 961,946 Ceded reinsurance claims (220,894) (284,937) (593,175) (736,824) Assumed reinsurance claims 5,504 — 9,589 (2) Total claims incurred, net $ 453,576 $ 85,392 $ 1,141,503 $ 225,120 The Company records selling, general and administrative expenses net of ceding commissions. The following table reconciles total other insurance costs to the amount presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Other insurance costs, gross $ 129,516 $ 70,283 $ 343,915 $ 216,106 Ceding commissions (18,214) (31,609) (57,986) (96,884) Other insurance costs, net $ 111,302 $ 38,674 $ 285,929 $ 119,222 The Company records reinsurance recoverables as “balances due from reinsurance programs” within current assets on its consolidated balance sheets. The composition of the reinsurance recoverables balance is as follows: September 30, 2021 December 31, 2020 (in thousands) Ceded reinsurance claim recoverables $ 378,921 $ 435,331 Reinsurance ceding commissions 27,559 41,586 Experience refunds on reinsurance agreements 7,309 102,476 Balances due from reinsurance programs $ 413,789 $ 579,393

REINSURANCE (Tables)

REINSURANCE (Tables)	9 Months Ended
	Sep. 30, 2021
Insurance [Abstract]
Schedule of premiums earned	Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct policy premiums $ 895,407 $ 584,811 $ 2,554,296 $ 1,737,267 Assumed premiums 3,830 — 9,426 — Direct and assumed premiums 899,237 584,811 2,563,722 1,737,267 Risk adjustment (225,777) (170,306) (556,236) (504,774) Premiums before ceded reinsurance 673,460 414,505 2,007,486 1,232,493 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Total premiums earned $ 441,743 $ 99,145 $ 1,338,439 $ 298,120 The following table summarizes the amounts of direct policy premiums received directly from CMS as part of APTC and Medicare Advantage for the three and nine months ended September 30, 2021 and 2020: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) APTC $ 668,647 $ 348,229 $ 1,812,335 $ 1,025,021 Medicare Advantage 9,969 4,477 29,472 12,622 Total paid by CMS $ 678,616 $ 352,706 $ 1,841,807 $ 1,037,643 The composition of total reinsurance premiums ceded and reinsurance premiums assumed, which are included as components of total premiums earned in the consolidated statement of operations, is as follows: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Reinsurance premiums ceded, gross $ (220,472) $ (338,685) $ (724,512) $ (1,002,822) Experience refunds (11,245) 23,325 55,465 68,449 Reinsurance premiums ceded (231,717) (315,360) (669,047) (934,373) Reinsurance premiums assumed 3,830 — 9,426 — Total reinsurance premiums (ceded) and assumed $ (227,887) $ (315,360) $ (659,621) $ (934,373) The Company records claims expense net of reinsurance recoveries. The following table reconciles the total claims expense to the net claims expense as presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Direct claims incurred $ 668,966 $ 370,329 $ 1,725,089 $ 961,946 Ceded reinsurance claims (220,894) (284,937) (593,175) (736,824) Assumed reinsurance claims 5,504 — 9,589 (2) Total claims incurred, net $ 453,576 $ 85,392 $ 1,141,503 $ 225,120 The Company records selling, general and administrative expenses net of ceding commissions. The following table reconciles total other insurance costs to the amount presented in the consolidated statement of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Other insurance costs, gross $ 129,516 $ 70,283 $ 343,915 $ 216,106 Ceding commissions (18,214) (31,609) (57,986) (96,884) Other insurance costs, net $ 111,302 $ 38,674 $ 285,929 $ 119,222 The Company records reinsurance recoverables as “balances due from reinsurance programs” within current assets on its consolidated balance sheets. The composition of the reinsurance recoverables balance is as follows: September 30, 2021 December 31, 2020 (in thousands) Ceded reinsurance claim recoverables $ 378,921 $ 435,331 Reinsurance ceding commissions 27,559 41,586 Experience refunds on reinsurance agreements 7,309 102,476 Balances due from reinsurance programs $ 413,789 $ 579,393

RESTRICTED CASH AND RESTRICTE_2

RESTRICTED CASH AND RESTRICTED DEPOSITS (Tables)	9 Months Ended
	Sep. 30, 2021
Cash and Cash Equivalents [Abstract]
Schedule of restricted deposits	The restricted cash and cash equivalents and restricted investments presented below are included in “restricted deposits” in the accompanying consolidated balance sheets. September 30, 2021 December 31, 2020 (in thousands) Restricted cash and cash equivalents $ 21,243 $ 16,779 Restricted investments 6,514 9,699 Restricted Deposits $ 27,757 $ 26,478

INVESTMENTS (Tables)

INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Summary of investments	The following tables provide summaries of the Company's investments by major security type at September 30, 2021 and December 31, 2020: September 30, 2021 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) U.S. treasury and agency securities $ 859,612 $ 246 $ (105) $ 859,753 Corporate notes 466,189 114 (244) 466,059 Certificate of deposit 26,623 — — 26,623 Commercial paper 35,538 — — 35,538 Municipalities 37,285 1 (32) 37,254 Total $ 1,425,247 $ 361 $ (381) $ 1,425,227 December 31, 2020 Amortized Cost Unrealized Gains Unrealized Losses Fair Value (in thousands) U.S. treasury and agency securities $ 523,809 $ 562 $ (2) $ 524,369 Corporate notes 159,461 262 (58) 159,665 Commercial paper 7,043 — — 7,043 Certificate of deposit 1,050 — — 1,050 Total $ 691,363 $ 824 $ (60) $ 692,127
Summary of investments in a gross unrealized loss position	At September 30, 2021 and December 31, 2020, the available-for-sale securities that mature within one year or less in a gross unrealized loss position are as follows: September 30, 2021 Number of Securities Fair Value Gross (in thousands) Investments twelve months or less: U.S. treasury and agency securities 60 $ 327,422 $ — Corporate notes 150 185,724 (42) Municipalities 38 $ 13,268 (5) Total 248 $ 526,414 $ (47) December 31, 2020 Number of Securities Fair Value Gross (in thousands) Investments twelve months or less: U.S. treasury and agency securities 51 $ 339,014 $ (2) Corporate notes 40 19,280 (3) Total 91 $ 358,294 $ (5) At September 30, 2021 and December 31, 2020, the available-for-sale securities that mature over twelve months or more in a gross unrealized loss position are as follows: September 30, 2021 Number of Securities Fair Value Gross (in thousands) Investments over twelve months: U.S. treasury and agency securities 47 $ 532,331 $ (105) Corporate notes 215 280,336 (202) Municipalities 57 $ 23,986 $ (27) Total 319 $ 836,653 $ (334) December 31, 2020 Number of Securities Fair Value Gross (in thousands) Investments over twelve months: Corporate notes 189 140,384 (55) Total 189 $ 140,384 $ (55)
Summary of investment income	Net investment income was attributable to the following: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Interest income $ 3,125 $ 2,018 $ 7,054 $ 6,500 Investment discount amortization net of premium accretion (2,458) (1,035) (5,520) (1,511) Net realized gain (loss) 21 489 271 936 Total $ 688 $ 1,472 $ 1,805 $ 5,925

FAIR VALUE (Tables)

FAIR VALUE (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities measured on recurring basis	Assets and liabilities measured at fair value on recurring basis are as follows: September 30, 2021 (Level 1) (Level 2) (Level 3) Total Fair Value Measurement (in thousands) Investments U.S. treasury and agency securities $ — $ 859,753 $ — $ 859,753 Corporate notes — 466,059 — 466,059 Commercial paper — 35,538 — 35,538 Certificate of deposit — 26,623 — 26,623 Municipalities — 37,254 — 37,254 Total $ — $ 1,425,227 $ — $ 1,425,227 December 31, 2020 (Level 1) (Level 2) (Level 3) Total Fair Value Measurement (in thousands) Investments U.S. treasury and agency securities $ — $ 524,369 $ — $ 524,369 Corporate notes — 159,665 — 159,665 Commercial paper — 7,043 — 7,043 Certificate of deposit — 1,050 — 1,050 Total $ — $ 692,127 $ — $ 692,127 Warrant liabilities $ — $ — $ 15,005 $ 15,005
Reconciliation of derivative liabilities measured on recurring basis	The table below presents changes in the fair value of the Company’s Level 3 warrant liabilities at September 30, 2021 and December 31, 2020 as follows: September 30, 2021 December 31, 2020 (in thousands) Beginning balance $ 15,005 $ 8,819 Vesting of warrants — 392 Change in fair value 13,243 4,709 Preferred Stock Series A11 call options issued — 13,488 Preferred Stock Series A11 call options exercised (70) (12,403) Preferred Stock Series AA, A8, and A9 exercised (28,178) — Ending balance $ — $ 15,005

BENEFITS PAYABLE (Tables)

BENEFITS PAYABLE (Tables)	9 Months Ended
	Sep. 30, 2021
Insurance [Abstract]
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense	The following table provides a rollforward of the Company’s beginning and ending benefits payable and claims adjustment expenses ("CAE") payable balances for the nine months ended September 30, 2021 and 2020: As of September 30, 2021 Benefits Payable Unallocated Claims Total (in thousands) Benefits payable, beginning of the period $ 311,914 $ 5,509 $ 317,423 Less: Reinsurance recoverable 132,658 — 132,658 Benefits payable, beginning of the period, net $ 179,256 $ 5,509 $ 184,765 Claims incurred and CAE Current year $ 1,151,734 $ 43,239 $ 1,194,973 Prior years (10,231) — (10,231) Total claims incurred and CAE, net $ 1,141,503 $ 43,239 $ 1,184,742 Claims paid and CAE Current year $ 885,043 $ 34,428 $ 919,471 Prior years 100,091 5,509 105,600 Total claims and CAE paid, net $ 985,134 $ 39,937 $ 1,025,071 Benefits and CAE payable, end of period, net $ 335,625 $ 8,811 $ 344,436 Add: Reinsurance recoverable 161,699 — 161,699 Benefits and CAE payable, end of period $ 497,324 $ 8,811 $ 506,135 As of September 30, 2020 Benefits Payable Unallocated Claims Total (in thousands) Benefits payable, beginning of the period $ 156,557 $ 3,009 $ 159,566 Less: Reinsurance recoverable 76,183 — 76,183 Benefits payable, beginning of the period, net $ 80,374 $ 3,009 $ 83,383 Claims incurred and CAE Current year $ 232,686 $ 33,262 $ 265,948 Prior years (7,566) — (7,566) Total claims incurred and CAE, net $ 225,120 $ 33,262 $ 258,382 Claims paid and CAE Current year $ 189,281 $ 28,410 $ 217,691 Prior years 30,835 3,009 33,844 Total claims and CAE paid, net $ 220,116 $ 31,419 $ 251,535 Benefits and CAE payable, end of period, net $ 85,378 $ 4,852 $ 90,230 Add: Reinsurance recoverable 191,134 — 191,134 Benefits and CAE payable, end of period $ 276,512 $ 4,852 $ 281,364

DEBT AND WARRANTS (Tables)

DEBT AND WARRANTS (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of outstanding warrants	The following table presents relevant information regarding outstanding warrants and call options: Warrant Type Issue Date Warrants Issued Issue Price Maximum No. of Preferred Stock Issuable Warrants Outstanding as of 12/31/20 Warrants Outstanding as of 9/30/21 Series AA Warrant 2013 629,152 $ 0.56 629,152 629,152 — Series A8 Warrant 2017 166,666 $ 6.75 166,666 166,666 — Series A9 Warrant 2018 416,666 $ 7.13 416,666 416,666 — Series A11 Call Options 2020 4,143,028 $ 6.02 4,143,028 12,732 — 1,225,216

CONVERTIBLE PREFERRED STOCK (Ta

CONVERTIBLE PREFERRED STOCK (Tables)	9 Months Ended
	Sep. 30, 2021
Temporary Equity Disclosure [Abstract]
Schedule of temporary equity	The table below presents relevant information relating to convertible preferred stock for the periods presented: December 31, 2020 September 30, 2021 Preferred Stock Preferred Stock Outstanding (pre-split) Preferred Stock Converted to Common Stock (Series A/B) (pre-split) Preferred Stock Outstanding A 41,913,800 (41,913,800) — A1 1,371,010 (1,371,010) — AA 22,379,980 (22,379,980) — AAA 36,109,790 (36,109,790) — A4 23,142,080 (23,142,080) — A5 29,189,760 (29,189,760) — A6 29,942,474 (29,942,474) — A7 6,265,845 (6,265,845) — A8 56,434,363 (56,434,363) — A9 23,177,793 (23,177,793) — AA-9 11,820,502 (11,820,502) — A10 53,877,952 (53,877,952) — A11 49,678,169 (49,678,169) — A12 15,600,784 (15,600,784) — Total 400,904,302 (400,904,302) —

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Summary of stock-based compensation expense	The following table summarizes the stock-based compensation expense for the three and nine months ended September 30, 2021 and 2020, which is included within the line items specified below in the consolidated statements of operations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Other insurance costs $ 10,122 $ 3,785 $ 28,988 $ 11,144 General and administrative expenses 10,518 3,502 29,040 10,840 Total stock-based compensation expense $ 20,640 $ 7,287 $ 58,028 $ 21,984
Summary of stock option award activity	The following table summarizes the stock option award activity under the 2012 Plan and 2021 Plan for the nine months ended September 30, 2021: September 30, 2021 Number of Options Weighted Average Exercise Price Weighted Average Contractual Life (in years) Aggregate Intrinsic Value (in thousands) Options Outstanding - December 31, 2020 41,115,486 $ 9.19 7.59 $ 279,477 Options granted 2,477,088 $ 22.49 Options exercised (5,990,310) $ 7.36 $ 106,326 Options canceled (2,417,301) $ 18.12 Options Outstanding - September 30, 2021 35,184,963 $ 10.21 7.17 $ 265,197 Options Exercisable at September 30, 2021 21,844,883 $ 8.37 6.23 $ 197,406
Summary of stock option valuation assumptions	The table below summarizes the assumptions used: September 30, 2021 Term in years 6.03 years Dividend rate — % Risk free rate of return 0.86 % Volatility 41.63 %
Summary of RSU activity	The following table summarizes RSU award activity for the nine months ended September 30, 2021: RSUs Number of Shares Weighted Average Grant Date Fair Value Outstanding RSUs at December 31, 2020 1,555,666 $ 15.82 RSUs granted 7,103,359 $ 17.82 RSUs vested (246,907) $ 23.31 RSUs canceled (165,017) $ 21.71 Outstanding RSUs at September 30, 2021 8,247,101 $ 17.20
Summary of PSU activity	The following table summarizes PSU award activity for the nine months ended September 30, 2021: PSU Number of Shares Weighted Average Grant Date Fair Value Outstanding PSUs at December 31, 2020 — $ — PSUs granted 7,082,432 $ 14.37 PSUs canceled — $ — Outstanding PSUs at September 30, 2021 7,082,432 $ 14.37

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of basic and diluted earnings per share	The following table presents the computation of basic and diluted earnings per share: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands, except share and per share data) Numerator : Net loss attributable to common stockholders $ (212,745) $ (79,132) $ (373,184) $ (216,955) Denominator : Weighted average shares of common stock outstanding, basic and diluted 208,159,343 29,042,932 168,585,157 28,941,215 Net loss per share, basic and diluted $ (1.02) $ (2.72) $ (2.21) $ (7.50)

VARIABLE INTEREST ENTITIES (Tab

VARIABLE INTEREST ENTITIES (Tables)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of variable interest entities	The following table presents the collective assets and liabilities of the professional corporations: September 30, 2021 December 31, 2020 (in thousands) Assets $ 2,240 $ 1,862 Liabilities $ 11,762 $ 7,589 The following table presents the collective revenues and operating expenses of the professional corporations: Three Months Ended Nine Months Ended September 30, 2021 September 30, 2020 September 30, 2021 September 30, 2020 (in thousands) Revenues $ 3,402 $ 1,824 $ 9,189 $ 5,122 Operating expenses $ 4,119 $ 3,129 $ 12,768 $ 9,004

ORGANIZATION (Details)

ORGANIZATION (Details) $ / shares in Units, $ in Millions	Mar. 05, 2021USD ($)$ / sharesshares	Mar. 03, 2021$ / sharesshares	Sep. 30, 2021segment$ / sharesshares	Mar. 02, 2021shares
Subsidiary, Sale of Stock [Line Items]
Number of operating segments | segment			1
Stock split, conversion ratio		0.33
Conversion of stock, shares converted			400,904,302
IPO
Subsidiary, Sale of Stock [Line Items]
Sale of stock, net proceeds | $	$ 1,300
Sale of stock, discounts and commissions | $	$ 71
Treasury stock reclassified to Class A | Treasury Stock
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted		943,800
Class A
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.00001	$ 0.00001
Stock split, conversion ratio		3
Common stock, shares outstanding		132,760,639	174,056,898	398,283,107
Class A | IPO
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction	36,391,946
Stock price (in dollars per share) | $ / shares	$ 39
Class A | Treasury stock reclassified to Class A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares issued		314,600
Class B
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.00001	$ 0.00001
Stock split, conversion ratio		3
Common stock, shares outstanding		35,335,579	35,115,807	106,006,786

PREMIUMS EARNED (Details)

PREMIUMS EARNED (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Effects of Reinsurance [Line Items]
Direct policy premiums	$ 895,407	$ 584,811	$ 2,554,296	$ 1,737,267
Assumed premiums	3,830	0	9,426	0
Direct and assumed premiums	899,237	584,811	2,563,722	1,737,267
Risk adjustment	(225,777)	(170,306)	(556,236)	(504,774)
Premiums before ceded reinsurance	673,460	414,505	2,007,486	1,232,493
Reinsurance premiums ceded	(231,717)	(315,360)	(669,047)	(934,373)
Premiums earned	441,743	99,145	1,338,439	298,120
CMS
Effects of Reinsurance [Line Items]
Direct policy premiums	678,616	352,706	1,841,807	1,037,643
CMS | APTC
Effects of Reinsurance [Line Items]
Direct policy premiums	668,647	348,229	1,812,335	1,025,021
CMS | Medicare Advantage
Effects of Reinsurance [Line Items]
Direct policy premiums	$ 9,969	$ 4,477	$ 29,472	$ 12,622

REINSURANCE (Details)

REINSURANCE (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)entity	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)entity	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Insurance [Abstract]
Number of reinsurers | entity	1		1
Premiums Earned, Net [Abstract]
Reinsurance premiums ceded, gross	$ (220,472)	$ (338,685)	$ (724,512)	$ (1,002,822)
Experience refunds	(11,245)	23,325	55,465	68,449
Reinsurance premiums ceded	(231,717)	(315,360)	(669,047)	(934,373)
Assumed premiums	3,830	0	9,426	0
Total reinsurance premiums (ceded) and assumed	(227,887)	(315,360)	(659,621)	(934,373)
Policyholder Benefits and Claims Incurred, Net [Abstract]
Direct claims incurred	668,966	370,329	1,725,089	961,946
Ceded reinsurance claims	(220,894)	(284,937)	(593,175)	(736,824)
Assumed reinsurance claims	5,504	0	9,589	(2)
Total claims incurred, net	453,576	85,392	1,141,503	225,120
Other Insurance Cost, Net [Abstract]
Other insurance costs, gross	129,516	70,283	343,915	216,106
Ceding commissions	(18,214)	(31,609)	(57,986)	(96,884)
Other insurance costs, net	111,302	$ 38,674	285,929	$ 119,222
Reinsurance Recoverables, Including Reinsurance Premium Paid [Abstract]
Ceded reinsurance claim recoverables	378,921		378,921		$ 435,331
Reinsurance ceding commissions	27,559		27,559		41,586
Experience refunds on reinsurance agreements	7,309		7,309		102,476
Balances due from reinsurance programs	$ 413,789		$ 413,789		$ 579,393

RESTRICTED CASH AND RESTRICTE_3

RESTRICTED CASH AND RESTRICTED DEPOSITS (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Cash and Cash Equivalents [Abstract]
Restricted cash and cash equivalents	$ 21,243	$ 16,779
Restricted investments	6,514	9,699
Restricted Deposits	$ 27,757	$ 26,478

INVESTMENTS - Summary of invest

INVESTMENTS - Summary of investments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,425,247	$ 691,363
Unrealized Gains	361	824
Unrealized Losses	(381)	(60)
Fair Value	1,425,227	692,127
U.S. treasury and agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	859,612	523,809
Unrealized Gains	246	562
Unrealized Losses	(105)	(2)
Fair Value	859,753	524,369
Corporate notes
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	466,189	159,461
Unrealized Gains	114	262
Unrealized Losses	(244)	(58)
Fair Value	466,059	159,665
Certificate of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	26,623	1,050
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	26,623	1,050
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	35,538	7,043
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	35,538	$ 7,043
Municipalities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	37,285
Unrealized Gains	1
Unrealized Losses	(32)
Fair Value	$ 37,254

INVESTMENTS - Summary of inve_2

INVESTMENTS - Summary of investments in a gross unrealized loss position (Details) $ in Thousands	Sep. 30, 2021USD ($)security	Dec. 31, 2020USD ($)security
Investments twelve months or less:
Number of Securities | security	248	91
Fair Value	$ 526,414	$ 358,294
Gross Unrealized Losses	$ (47)	$ (5)
Investments over twelve months:
Number of Securities | security	319	189
Fair Value	$ 836,653	$ 140,384
Gross Unrealized Losses	$ (334)	$ (55)
U.S. treasury and agency securities
Investments twelve months or less:
Number of Securities | security	60	51
Fair Value	$ 327,422	$ 339,014
Gross Unrealized Losses	$ 0	$ (2)
Investments over twelve months:
Number of Securities | security	47
Fair Value	$ 532,331
Gross Unrealized Losses	$ (105)
Corporate notes
Investments twelve months or less:
Number of Securities | security	150	40
Fair Value	$ 185,724	$ 19,280
Gross Unrealized Losses	$ (42)	$ (3)
Investments over twelve months:
Number of Securities | security	215	189
Fair Value	$ 280,336	$ 140,384
Gross Unrealized Losses	$ (202)	$ (55)
Municipalities
Investments twelve months or less:
Number of Securities | security	38
Fair Value	$ 13,268
Gross Unrealized Losses	$ (5)
Investments over twelve months:
Number of Securities | security	57
Fair Value	$ 23,986
Gross Unrealized Losses	$ (27)

INVESTMENTS - Summary of inve_3

INVESTMENTS - Summary of investment income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Investments, Debt and Equity Securities [Abstract]
Interest income	$ 3,125	$ 2,018	$ 7,054	$ 6,500
Investment amortization, net of accretion	(2,458)	(1,035)	(5,520)	(1,511)
Net realized gain (loss)	21	489	271	936
Total	$ 688	$ 1,472	$ 1,805	$ 5,925

FAIR VALUE - Schedule of assets

FAIR VALUE - Schedule of assets and liabilities measured on recurring basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 1,425,227	$ 692,127
Warrant liabilities	0	15,005
U.S. treasury and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	859,753	524,369
Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	466,059	159,665
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	35,538	7,043
Certificate of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	26,623	1,050
Municipalities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	37,254
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,425,227	692,127
Warrant liabilities		15,005
Recurring | U.S. treasury and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	859,753	524,369
Recurring | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	466,059	159,665
Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	35,538	7,043
Recurring | Certificate of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	26,623	1,050
Recurring | Municipalities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	37,254
(Level 1) | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Warrant liabilities		0
(Level 1) | Recurring | U.S. treasury and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
(Level 1) | Recurring | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
(Level 1) | Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
(Level 1) | Recurring | Certificate of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
(Level 1) | Recurring | Municipalities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
(Level 2) | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,425,227	692,127
Warrant liabilities		0
(Level 2) | Recurring | U.S. treasury and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	859,753	524,369
(Level 2) | Recurring | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	466,059	159,665
(Level 2) | Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	35,538	7,043
(Level 2) | Recurring | Certificate of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	26,623	1,050
(Level 2) | Recurring | Municipalities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	37,254
(Level 3) | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Warrant liabilities		15,005
(Level 3) | Recurring | U.S. treasury and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
(Level 3) | Recurring | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
(Level 3) | Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
(Level 3) | Recurring | Certificate of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	$ 0
(Level 3) | Recurring | Municipalities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 0

FAIR VALUE - Reconciliation of

FAIR VALUE - Reconciliation of derivatives measured on recurring basis (Details) - Warrant - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 15,005	$ 8,819
Vesting of warrants	0	392
Change in fair value	13,243	4,709
Preferred Stock Series A11 call options issued	0	13,488
Ending balance	0	15,005
Series A11
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Preferred Stock exercised	(70)	(12,403)
Series AA, A8, and A9 Preferred Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Preferred Stock exercised	$ (28,178)	$ 0

BENEFITS PAYABLE (Details)

BENEFITS PAYABLE (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Benefits payable, beginning of period	$ 311,914	$ 156,557
CAE payable, beginning of the period	5,509	3,009
Benefits and CAE payable, beginning of period	506,135	281,364	$ 317,423	$ 159,566
Less: Reinsurance recoverable	132,658	76,183
Benefits payable, net reinsurance recoverable, beginning of period	179,256	80,374
Benefits and CAE payable, net, beginning of period	184,765	83,383
Benefits Payable
Current year	1,151,734	232,686
Prior years	(10,231)	(7,566)
Claims incurred	1,141,503	225,120
Unallocated Claims Adjustment Expense
Current year	43,239	33,262
Prior years	0	0
Claims adjustment expense	43,239	33,262
Total
Current year	1,194,973	265,948
Prior years	(10,231)	(7,566)
Total claims incurred and CAE, net	1,184,742	258,382
Benefits Payable
Current year	885,043	189,281
Prior years	100,091	30,835
Claims paid	985,134	220,116
Unallocated Claims Adjustment Expense
Current year	34,428	28,410
Prior years	5,509	3,009
CAE paid	39,937	31,419
Total
Current year	919,471	217,691
Prior years	105,600	33,844
Total claims and CAE paid, net	1,025,071	251,535
Benefits payable, net reinsurance recoverable, end of period	335,625	85,378
CAE payable, end of the period	8,811	4,852
Benefits and CAE payable, net, end of period	344,436	90,230
Add: Reinsurance recoverable	161,699	191,134
Benefits payable, end of period	497,324	276,512
Benefits and CAE payable, end of period	$ 506,135	$ 281,364

DEBT AND WARRANTS - Narrative (

DEBT AND WARRANTS - Narrative (Details) - USD ($)	Mar. 05, 2021	Feb. 21, 2021	Oct. 30, 2020	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Debt repayment							$ 153,173,000	$ 0
Debt extinguishment loss				$ 0		$ 0	20,178,000	0
Debt prepayment cost							12,994,000	0
Gain (loss) on fair value of warrant liabilities							$ (12,856,000)	$ 509,000
Class A | Common Stock
Debt Instrument [Line Items]
Issuance of common stock upon exercise of warrants and call options (in shares)	1,115,973				1,115,973
Loan payable | Facility Agreement
Debt Instrument [Line Items]
Aggregate principal amount			$ 150,000,000
Interest rate during period							12.75%
Debt repayment	$ 153,200,000
Paid-in-kind interest	3,200,000
Debt extinguishment loss	20,200,000
Debt prepayment cost	13,000,000
Unamortized debt discount and issuance costs written off	$ 7,200,000
Loan payable | LIBOR | Facility Agreement
Debt Instrument [Line Items]
Basis spread on variable rate			11.75%
Line of credit | Revolving credit facility | Revolving Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 200,000,000
Borrowing capacity, increase limit		$ 50,000,000
Commitment fee		0.50%
Line of credit outstanding				$ 0			$ 0
Line of credit | Revolving credit facility | LIBOR | Revolving Credit Agreement
Debt Instrument [Line Items]
Basis spread on variable rate		4.50%
Line of credit | Revolving credit facility | Alternative Base Rate | Revolving Credit Agreement
Debt Instrument [Line Items]
Basis spread on variable rate		3.50%
Line of credit | Revolving credit facility | Fed funds effective rate | Revolving Credit Agreement
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Line of credit | Revolving credit facility | Adjusted LIBOR | Revolving Credit Agreement
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%

DEBT AND WARRANTS - Schedule of

DEBT AND WARRANTS - Schedule of outstanding warrants (Details) - $ / shares	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)		1,225,216
Series AA Warrant
Class of Warrant or Right [Line Items]
Warrants issued (in shares)					629,152
Warrant issue price (in dollars per share)					$ 0.56
Maximum number of preferred stock issuable (in shares)					629,152
Warrants outstanding (in shares)	0	629,152
Series A8 Warrant
Class of Warrant or Right [Line Items]
Warrants issued (in shares)				166,666
Warrant issue price (in dollars per share)				$ 6.75
Maximum number of preferred stock issuable (in shares)				166,666
Warrants outstanding (in shares)	0	166,666
Series A9 Warrant
Class of Warrant or Right [Line Items]
Warrants issued (in shares)			416,666
Warrant issue price (in dollars per share)			$ 7.13
Maximum number of preferred stock issuable (in shares)			416,666
Warrants outstanding (in shares)	0	416,666
Series A11 Call Options
Class of Warrant or Right [Line Items]
Warrants issued (in shares)		4,143,028
Warrant issue price (in dollars per share)		$ 6.02
Maximum number of preferred stock issuable (in shares)		4,143,028
Warrants outstanding (in shares)	0	12,732

CONVERTIBLE PREFERRED STOCK (De

CONVERTIBLE PREFERRED STOCK (Details)	9 Months Ended
	Sep. 30, 2021shares
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	400,904,302
Conversion of stock, shares converted	(400,904,302)
Ending balance (in shares)	0
Series A
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	41,913,800
Conversion of stock, shares converted	(41,913,800)
Ending balance (in shares)	0
Series A1
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	1,371,010
Conversion of stock, shares converted	(1,371,010)
Ending balance (in shares)	0
Series AA
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	22,379,980
Conversion of stock, shares converted	(22,379,980)
Ending balance (in shares)	0
Series AAA
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	36,109,790
Conversion of stock, shares converted	(36,109,790)
Ending balance (in shares)	0
Series A4
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	23,142,080
Conversion of stock, shares converted	(23,142,080)
Ending balance (in shares)	0
Series A5
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	29,189,760
Conversion of stock, shares converted	(29,189,760)
Ending balance (in shares)	0
Series A6
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	29,942,474
Conversion of stock, shares converted	(29,942,474)
Ending balance (in shares)	0
Series A7
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	6,265,845
Conversion of stock, shares converted	(6,265,845)
Ending balance (in shares)	0
Series A8
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	56,434,363
Conversion of stock, shares converted	(56,434,363)
Ending balance (in shares)	0
Series A9
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	23,177,793
Conversion of stock, shares converted	(23,177,793)
Ending balance (in shares)	0
Series AA-9
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	11,820,502
Conversion of stock, shares converted	(11,820,502)
Ending balance (in shares)	0
Series A10
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	53,877,952
Conversion of stock, shares converted	(53,877,952)
Ending balance (in shares)	0
Series A11
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	49,678,169
Conversion of stock, shares converted	(49,678,169)
Ending balance (in shares)	0
Series A12
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)	15,600,784
Conversion of stock, shares converted	(15,600,784)
Ending balance (in shares)	0

STOCKHOLDERS' EQUITY (Details)

STOCKHOLDERS' EQUITY (Details) $ / shares in Units, $ in Millions	Mar. 05, 2021USD ($)$ / sharesshares	Mar. 03, 2021$ / sharesshares	Mar. 02, 2021$ / sharesshares	Sep. 30, 2021vote$ / sharesshares	Dec. 31, 2020$ / sharesshares
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted				400,904,302
Preferred stock, shares authorized		82,500,000		82,500,000
Stock split, conversion ratio		0.33
IPO
Subsidiary, Sale of Stock [Line Items]
Sale of stock, net proceeds | $	$ 1,300
Sale of stock, discounts and commissions | $	$ 71
Preferred Stock converted to Series A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted			402,192,500
Class A
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.00001		$ 0.00001
Common stock, shares authorized		825,000,000		825,000,000
Common stock, conversion ratio				1
Stock split, conversion ratio		3
Common stock, shares outstanding		132,760,639	398,283,107	174,056,898
Voting rights, number of votes | vote				1
Class A | IPO
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction	36,391,946
Stock price (in dollars per share) | $ / shares	$ 39
Class A | Series A reclassified to Class A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares issued			398,283,107
Class A | Class B converted to Class A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares issued		219,772
Series A common stock
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares			$ 0.00001		$ 0.00001
Common stock, shares authorized					680,000,000
Common stock, shares outstanding					8,291,917
Series A common stock | Preferred Stock converted to Series A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares issued			403,261,643
Series A common stock | Series B converted to Series A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares issued			9,360,800
Series A common stock | Series A reclassified to Class A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted			398,283,107
Series A common stock | Series A reclassified to Class B
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted			45,879,623
Series B common stock
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares			$ 0.00001		$ 0.00001
Common stock, shares authorized					69,487,963
Common stock, shares outstanding					23,162,654
Series B common stock | Series B converted to Series A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted			9,360,800
Series B common stock | Series B reclassified to Class B
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted			60,127,163
Class B
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.00001		$ 0.00001
Common stock, shares authorized		82,500,000		82,500,000
Common stock, conversion ratio				1
Stock split, conversion ratio		3
Common stock, shares outstanding		35,335,579	106,006,786	35,115,807
Voting rights, number of votes | vote				20
Class B | Series B reclassified to Class B
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares issued			60,127,163
Class B | Series A reclassified to Class B
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares issued			45,879,623
Class B | Class B converted to Class A
Subsidiary, Sale of Stock [Line Items]
Conversion of stock, shares converted		219,772

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of stock-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 20,640	$ 7,287	$ 58,028	$ 21,984
Other insurance costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	10,122	3,785	28,988	11,144
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 10,518	$ 3,502	$ 29,040	$ 10,840

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, weighted average grant date fair value (in dollars per share)			$ 8.98
Stock-based compensation expense	$ 20,640	$ 7,287	$ 58,028	$ 21,984
Unrecognized compensation expense, options	62,400		$ 62,400
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contractual term			10 years
Award vesting period			4 years
Stock-based compensation expense	7,800	$ 7,300	$ 30,500	$ 22,000
Unrecognized compensation expense, period for recognition			2 years 8 months 12 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	7,200		$ 15,100
Unrecognized compensation expense, period for recognition			3 years
Unrecognized compensation expense	132,000		$ 132,000
RSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			1 year
RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	5,700		$ 12,500
Unrecognized compensation expense, period for recognition			3 years 10 months 24 days
Unrecognized compensation expense	$ 89,200		$ 89,200
PSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			1 year
PSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			7 years

STOCK-BASED COMPENSATION - Su_2

STOCK-BASED COMPENSATION - Summary of stock option award activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Number of Options
Beginning balance (in shares) | shares	41,115,486
Options granted (in shares) | shares	2,477,088
Options exercised (in shares) | shares	(5,990,310)
Options canceled (in shares) | shares	(2,417,301)
Ending balance (in shares) | shares	35,184,963	41,115,486
Options exercisable (in shares) | shares	21,844,883
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 9.19
Options granted (in dollars per share) | $ / shares	22.49
Options exercised (in dollars per share) | $ / shares	7.36
Options canceled (in dollars per share) | $ / shares	18.12
Ending balance (in dollars per share) | $ / shares	10.21	$ 9.19
Options exercisable (in dollars per share) | $ / shares	$ 8.37
Weighted Average Contractual Life (in years)
Options outstanding, weighted average contractual life	7 years 2 months 1 day	7 years 7 months 2 days
Options exercisable, weighted average contractual life	6 years 2 months 23 days
Aggregate Intrinsic Value (in thousands)
Beginning balance, aggregate intrinsic value | $	$ 279,477
Options exercised, aggregate intrinsic value | $	106,326
Ending balance, aggregate intrinsic value | $	265,197	$ 279,477
Options exercisable, aggregate intrinsic value | $	$ 197,406

STOCK-BASED COMPENSATION - Su_3

STOCK-BASED COMPENSATION - Summary of valuation assumptions (Details) - Stock options	9 Months Ended
	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term in years	6 years 10 days
Dividend rate	0.00%
Risk free rate of return	0.86%
Volatility	41.63%

STOCK-BASED COMPENSATION - Su_4

STOCK-BASED COMPENSATION - Summary of RSU and PSU activity (Details) - $ / shares	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
RSUs
Number of Shares
Outstanding, beginning balance (in shares)	8,247,101	1,555,666
Granted (in shares)	7,103,359
Vested (in shares)	(246,907)
Canceled (in shares)	(165,017)
Outstanding, ending balance (in shares)	8,247,101
Weighted Average Grant Date Fair Value
Outstanding, beginning balance (in dollars per share)	$ 15.82
Granted (in dollars per share)	17.82
Vested (in dollars per share)	23.31
Canceled (in dollars per share)	21.71
Outstanding, ending balance (in dollars per share)	$ 17.20
PSUs
Number of Shares
Outstanding, beginning balance (in shares)	7,082,432	0
Granted (in shares)	7,082,432
Canceled (in shares)	0
Outstanding, ending balance (in shares)	7,082,432
Weighted Average Grant Date Fair Value
Outstanding, beginning balance (in dollars per share)	$ 0
Granted (in dollars per share)	14.37
Canceled (in dollars per share)	0
Outstanding, ending balance (in dollars per share)	$ 14.37

EARNINGS (LOSS) PER SHARE (Deta

EARNINGS (LOSS) PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (212,745)	$ (73,068)	$ (87,371)	$ (79,132)	$ (40,944)	$ (96,879)	$ (373,184)	$ (216,955)
Denominator:
Weighted average common shares outstanding, basic	208,159,343			29,042,932			168,585,157	28,941,215
Weighted-average common shares outstanding, diluted	208,159,343			29,042,932			168,585,157	28,941,215
Net loss per share, basic and diluted
Net loss per share, basic (in dollars per share)	$ (1.02)			$ (2.72)			$ (2.21)	$ (7.50)
Net loss per share, diluted (in dollars per share)	$ (1.02)			$ (2.72)			$ (2.21)	$ (7.50)

VARIABLE INTEREST ENTITIES (Det

VARIABLE INTEREST ENTITIES (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Variable Interest Entity [Line Items]
Assets	$ 3,169,880,000		$ 3,169,880,000		$ 2,272,106,000
Liabilities	1,616,668,000		1,616,668,000		1,823,088,000
Revenue	443,979,000	$ 101,700,000	$ 1,342,648,000	$ 305,128,000
VIE, Integrated Health Systems
Variable Interest Entity [Line Items]
VIE, ownership percentage			50.00%
VIE, Integrated Health Systems | Eliminations
Variable Interest Entity [Line Items]
Income (expense) through shared savings arrangements	4,500,000	0	$ 1,600,000	0
VIE, Professional Corporations
Variable Interest Entity [Line Items]
Assets	2,240,000		2,240,000		1,862,000
Liabilities	11,762,000		11,762,000		$ 7,589,000
Revenue	3,402,000	1,824,000	9,189,000	5,122,000
Operating expenses	$ 4,119,000	$ 3,129,000	$ 12,768,000	$ 9,004,000