Oak Street Health (OSH) 10-Q 16 Sep 20 2020 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Sep. 10, 2020
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Registrant Name	Oak Street Health, Inc.
Entity Central Index Key	0001564406
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	No
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Incorporation, State or Country Code	DE
Entity Address, Country	IL
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	OSH
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		17,968,750

Consolidated Balance sheets

Consolidated Balance sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Long-term assets:
Total assets	$ 0	$ 0
Long-term liabilities:
Commitments and Contingencies
Members' deficit:
Common Stock, par value $0.001 per share, 1,000 shares authorized, none issued or outstanding	0	0
Total stockholder's equity	0	0
OAK Street Health LLC and Affiliates [Member]
Current assets:
Cash	185,561	33,987
Restricted cash	10,391	8,266
Other patient service receivables (Humana comprised $58 and $66 as of June 30, 2020 and December 31, 2019, respectively)	789	729
Capitated accounts receivable (Humana comprised $46,775 and $49,647 as of June 30, 2020 and December 31, 2019, respectively)	243,227	167,429
Prepaid expenses	2,519	1,382
Other current assets	4,939	8,028
Total current assets	447,426	219,821
Long-term assets:
Property and equipment, net	70,479	67,396
Security deposits	1,414	1,494
Goodwill	9,634	9,634
Intangible assets, net	3,159	3,352
Other long-term assets	115	125
Total assets	532,227	301,822
Current liabilities:
Accounts payable	3,875	10,757
Accrued compensation and benefits	22,619	28,610
Liability for unpaid claims (Humana comprised $50,381 and $58,916 as of June 30, 2020 and December 31, 2019, respectively)	235,856	170,629
Other liabilities (Humana comprised $6,113 and $5,294 as of June 30, 2020 and December 31, 2019, respectively)	17,078	11,001
Current portion of long-term debt		18,507
Total current liabilities	279,428	239,504
Long-term liabilities:
Deferred rent expense (Humana comprised $1,074 and $1,034 as of June 30, 2020 and December 31, 2019, respectively)	13,015	12,901
Other long-term liabilities (Humana comprised $6,066 and $4,705 as of June 30, 2020 and December 31, 2019, respectively)	13,970	10,816
Long-term debt, net of current portion	82,126	62,840
Total liabilities	388,539	326,061
Commitments and Contingencies
Redeemable Investor Units, aggregate liquidation preference of $643,173 and $397,009 as of June 30, 2020 and December 31, 2019, respectively (Humana comprised $57,233 and $55,084 as of June 30, 2020 and December 31, 2019, respectively)	545,001	320,639
Members' deficit:
Members' capital, par value $0.01 per unit, 11,000,000 units authorized as of June 30, 2020 and December 31, 2019 (3,461,460 and 2,530,864 units issued and outstanding at June 30, 2020 and December 31, 2019, respectively)	3,454	4,192
Accumulated deficit	(409,618)	(354,355)
Total members' deficit allocated to the Company	(406,164)	(350,163)
Non-controlling interests	4,851	5,285
Total members' deficit	(401,313)	(344,878)
Total liabilities, redeemable investor units and members' deficit	$ 532,227	$ 301,822

Consolidated Balance sheets (Pa

Consolidated Balance sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Members capital par value or stated value per unit	$ 0.001	$ 0.001
Member units authorised	1,000	1,000
Member Units Issued	0	0
Member units outstanding	0	0
OAK Street Health LLC and Affiliates [Member]
Other receivables current	$ 789	$ 729
Accounts receivable net current	243,227	167,429
Liability for unpaid claims	235,856	170,629
Other liabilities current	17,078	11,001
Deferred rent payable non current	13,015	12,901
Other long term liabilities non current	13,970	10,816
Temporary equity liquidation preference	$ 643,173	$ 397,009
Members capital par value or stated value per unit	$ 0.01	$ 0.01
Member units authorised	11,000,000	11,000,000
Member Units Issued	3,461,460	2,530,864
Member units outstanding	3,461,460	2,530,864
Humana [Member] | OAK Street Health LLC and Affiliates [Member]
Other receivables current	$ 58	$ 66
Accounts receivable net current	46,775	49,647
Liability for unpaid claims	50,381	58,916
Other liabilities current	6,113	5,294
Deferred rent payable non current	1,074	1,034
Other long term liabilities non current	6,066	4,705
Temporary equity liquidation preference	$ 57,233	$ 55,084

Consolidated Statements of Oper

Consolidated Statements of Operations - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total revenues	$ 214,382	$ 126,488	$ 416,167	$ 243,865
Operating expenses:
Sales and marketing	10,102	11,253	21,973	19,928
Corporate, general and administrative expenses	31,038	16,045	55,419	27,956
Depreciation and amortization	2,674	1,856	5,178	3,581
Loss from operations	(24,418)	(18,440)	(37,442)	(28,292)
Other income (expense):
Interest expense, net	(2,448)	(1,867)	(4,874)	(1,876)
Other	22	22	117	84
Net loss	(26,844)	(20,285)	(42,199)	(30,084)
Net loss attributable to non-controlling interests	79	124	434	(72)
Net loss attributable to the Company	(26,765)	(20,161)	(41,765)	(30,156)
Undeclared and deemed dividends	(12,230)	(7,188)	(21,802)	(14,302)
Net loss attributable to common unitholders	$ (38,995)	$ (27,349)	$ (63,567)	$ (44,458)
Weighted-average number of common units outstanding – basic and diluted	537,654	620,068	578,861	620,068
Net loss per unit – basic and diluted	$ (72.53)	$ (44.11)	$ (109.81)	$ (71.70)
Medical Claims Expenses [Member]
Operating expenses:
Cost of providing patient care in relation to revenue waived	$ 155,460	$ 84,345	$ 287,745	$ 161,619
Cost of Care [Member]
Operating expenses:
Cost of providing patient care in relation to revenue waived	39,526	31,429	83,294	59,073
Capitated Revenue [Member]
Total revenues	207,997	123,054	404,587	238,383
Other Patient Service Revenue [Member]
Total revenues	$ 6,385	$ 3,434	$ 11,580	$ 5,482

Consolidated Statements of Op_2

Consolidated Statements of Operations (Parenthetical) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total revenues	$ 214,382	$ 126,488	$ 416,167	$ 243,865
Medical Claims Expenses [Member]
Cost of providing patient care in relation to revenue waived	155,460	84,345	287,745	161,619
Cost of Care [Member]
Cost of providing patient care in relation to revenue waived	39,526	31,429	83,294	59,073
Capitated Revenue [Member]
Total revenues	207,997	123,054	404,587	238,383
Other Patient Service Revenue [Member]
Total revenues	6,385	3,434	11,580	5,482
Humana [Member] | Medical Claims Expenses [Member]
Cost of providing patient care in relation to revenue waived	63,973	50,771	123,818	99,372
Humana [Member] | Cost of Care [Member]
Cost of providing patient care in relation to revenue waived	1,235	869	2,405	1,559
Humana [Member] | Capitated Revenue [Member]
Total revenues	97,367	75,731	193,854	149,413
Humana [Member] | Other Patient Service Revenue [Member]
Total revenues	$ 809	$ 791	$ 1,591	$ 1,569

Consolidated Statements of Chan

Consolidated Statements of Changes in Redeemable Investor Units and Members' Deficit - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	Total	Redeemable Investor Units [Member]	Members' Capital [Member]	Accumulated Deficit [Member]	Non-controlling Interest [Member]
Redeemable Investor, Beginning balance at Dec. 31, 2018		$ 319,139
Beginning balance at Dec. 31, 2018	$ (241,810)		$ 463	$ (246,493)	$ 4,220
Beginning balance (In Shares) at Dec. 31, 2018		10,975,101	2,074,216
Issuance of Series I, II and III Investor Units		$ 1,500
Issuance of Series I, II and III Investor Units (In Shares)		25,518
Issuance of Common Units			244,120
Repurchases – Profits Interests			(7,987)
Forfeitures – Profits Interests	(96)		$ (96)
Forfeitures – Profits Interests (In Shares)			(16,331)
Unit-Based Compensation	637		$ 637
Payments from Non-controlling Interest	2,646				2,646
Net loss	(30,084)			(30,156)	72
Redeemable Investor, Ending balance at Jun. 30, 2019		$ 320,639
Ending balance at Jun. 30, 2019	(268,707)		$ 1,004	(276,649)	6,938
Ending balance (In Shares) at Jun. 30, 2019		11,000,619	2,294,018
Redeemable Investor, Beginning balance at Dec. 31, 2018		$ 319,139
Beginning balance at Dec. 31, 2018	$ (241,810)		$ 463	(246,493)	4,220
Beginning balance (In Shares) at Dec. 31, 2018		10,975,101	2,074,216
Issuance of Common Units	25,518
Redeemable Investor, Ending balance at Dec. 31, 2019	$ 320,639	$ 320,639
Ending balance at Dec. 31, 2019	(344,878)		$ 4,192	(354,355)	5,285
Ending balance (In Shares) at Dec. 31, 2019		11,000,619	2,530,864
Redeemable Investor, Beginning balance at Mar. 31, 2019		$ 319,139
Beginning balance at Mar. 31, 2019	(248,813)		$ 613	(256,488)	7,062
Beginning balance (In Shares) at Mar. 31, 2019		10,975,101	2,065,663
Issuance of Series I, II and III Investor Units		$ 1,500
Issuance of Series I, II and III Investor Units (In Shares)		25,518
Issuance of Common Units			244,120
Repurchases – Profits Interests			(4,690)
Forfeitures – Profits Interests	(21)		$ (21)
Forfeitures – Profits Interests (In Shares)			(11,075)
Unit-Based Compensation	412		$ 412
Net loss	(20,285)			(20,161)	(124)
Redeemable Investor, Ending balance at Jun. 30, 2019		$ 320,639
Ending balance at Jun. 30, 2019	(268,707)		$ 1,004	(276,649)	6,938
Ending balance (In Shares) at Jun. 30, 2019		11,000,619	2,294,018
Redeemable Investor, Beginning balance at Dec. 31, 2019	320,639	$ 320,639
Beginning balance at Dec. 31, 2019	$ (344,878)		$ 4,192	(354,355)	5,285
Beginning balance (In Shares) at Dec. 31, 2019		11,000,619	2,530,864
Issuance of Series I, II and III Investor Units		$ 224,363
Issuance of Series I, II and III Investor Units (In Shares)		1,471,623
Issuance of Common Units	1,471,623		1,095,067
Tender Offer	$ (19,393)		$ (5,895)	(13,498)
Tender Offer (In Shares)			(131,151)
Repurchases – Profits Interests			(2,031)
Forfeitures – Profits Interests	(132)		$ (132)
Forfeitures – Profits Interests (In Shares)			(31,289)
Unit-Based Compensation	5,289		$ 5,289
Net loss	(42,199)			(41,765)	(434)
Redeemable Investor, Ending balance at Jun. 30, 2020	545,001	$ 545,001
Ending balance at Jun. 30, 2020	(401,313)		$ 3,454	(409,618)	4,851
Ending balance (In Shares) at Jun. 30, 2020		12,472,242	3,461,460
Redeemable Investor, Beginning balance at Mar. 31, 2020		$ 545,001
Beginning balance at Mar. 31, 2020	(358,412)		$ 6,013	(369,355)	4,930
Beginning balance (In Shares) at Mar. 31, 2020		12,472,242	2,790,395
Issuance of Common Units			829,567
Tender Offer	(19,393)		$ (5,895)	(13,498)
Tender Offer (In Shares)			(131,151)
Repurchases – Profits Interests			(1,594)
Forfeitures – Profits Interests	(125)		$ (125)
Forfeitures – Profits Interests (In Shares)			(25,758)
Unit-Based Compensation	3,461		$ 3,461
Net loss	(26,844)			(26,765)	(79)
Redeemable Investor, Ending balance at Jun. 30, 2020	545,001	$ 545,001
Ending balance at Jun. 30, 2020	$ (401,313)		$ 3,454	$ (409,618)	$ 4,851
Ending balance (In Shares) at Jun. 30, 2020		12,472,242	3,461,460

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (42,199)	$ (30,084)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of discount on debt and related issuance costs	778	509
Depreciation and amortization	5,178	3,581
Unit-based compensation, net of forfeitures	5,157	541
Change in fair value of bifurcated derivative	297	(489)
Changes in operating assets and liabilities:
Accounts receivable	(75,858)	(21,611)
Prepaid expenses and other current assets	1,951	168
Security deposits and other long-term assets	91	(288)
Accounts payable	(6,907)	(491)
Liability for unpaid claims	65,227	21,357
Accrued compensation and benefits	(5,991)	3,073
Other current liabilities	6,077	1,216
Other long-term liabilities	2,857	(826)
Deferred rent expense	114	3,787
Net cash used in operating activities	(43,228)	(19,557)
Cash flows from investing activities:
Purchase of business		(166)
Purchases of property and equipment	(8,043)	(12,268)
Net cash used in investing activities	(8,043)	(12,434)
Cash flows from financing activities:
Proceeds from issuance of redeemable investor units	224,363	1,500
Proceeds from long-term debt		29,457
Capital contributions from non-controlling interests		2,646
Tender offer	(19,393)
Net cash provided by financing activities	204,970	33,603
Net change in cash, cash equivalents and restricted cash	153,699	1,612
Cash, cash equivalents and restricted cash, beginning of period	42,253	72,067
Cash, cash equivalents and restricted cash, end of period	195,952	73,679
Cash paid during the period for:
Interest	3,993	1,904
Additions to construction in process funded through accounts payable	$ 25	$ 2,153

Organization

Organization	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Oak Street Health, Inc. (the “Company”, “we”) was formed as a Delaware corporation on October 22, 2019. The Company was formed for the purpose of completing a public offering (“IPO”) and related transactions in order to carry on the business of Oak Street Health, LLC (“OSH LLC”) and affiliates.

Nature of Business

Nature of Business	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Nature of Business	NOTE 1. NATURE OF BUSINESS Basis of Presentation and Principles of Consolidation Oak Street Health, LLC (“Oak Street Health” or “OSH”) and Affiliates, collectively referred to as “we” or “us” or “our” or the “Company”, operates primary care centers serving Medicare beneficiaries. The Company, through its centers and management services organization, combines an innovative care model with superior patient experience. The Company invests resources into primary care to prevent unnecessary acute events and manage chronic illnesses. The Company engages Medicare eligible patients through the use of an innovative community outreach approach. Once patients are engaged, the Company integrates population health analytics, social support services and primary care into the care model to drive improved outcomes. The Company contracts with health plans to generate medical costs savings and realize a return on its investment in primary care. As of June 30, 2020, the Company operated 54 centers. Oak Street Health is organized as a limited liability company (“LLC”). As such, no member, agent or employee of the Company shall be personally liable for debts, obligations or liabilities of the Company, whether arising in contract, tort, or otherwise or for the acts or omissions of any other member, director, manager, agent or employee of the Company, unless the individual has agreed otherwise under the provisions of the Company’s operating agreement or signed a specific personal guarantee. The duration of the Company is perpetual. Oak Street Health, MSO LLC (“MSO”), a wholly owned subsidiary of Oak Street Health LLC, was formed in 2013 to provide a wide range of management services to the Physician Groups (as defined below). Activities include but are not limited to operational support of the centers, marketing, information technology infrastructure and the sourcing and managing of health plan contracts. Oak Street Health Physicians Group PC, OSH-IN OSH-MI OSH-OH OSH-PA OSH-RI In addition, Oak Street Health is the majority interest owner in three joint ventures: OSH-PCJ OSH-RI, OSH-ESC OSH-ESC The accompanying unaudited interim consolidated financial statements and accompanying notes have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q S-X. six-months COVID-19, The consolidated financial statements of Oak Street Health include the financial statements of all wholly owned subsidiaries and majority-owned or controlled companies. For those consolidated subsidiaries where our ownership is less than 100%, the portion of the net income or loss allocable to the non-controlling non-controlling Initial Public Offering On August 5, 2020, Oak Street Health, Inc.’s (OSH Inc.’s) Registration Statement on Form S-1 to register 17,968,750 shares of common stock , par value $0.001 per share, was declared effective by the Securities & Exchange Commission. OSH Inc.’s common stock began trading on August 6, 2020 on the New York Stock Exchange (“NYSE”) under the ticker symbol “OSH.” As a result, our consolidated financial statements as of June 30, 2020 do not reflect the impact of the IPO. On August 10, 2020, OSH Inc. completed its IPO in which it issued and shares of its common stock at an offering price per share. The share amount includes the exercise in full of the underwriters’ options to additional shares of common stock. OSH Inc. received net proceeds after deducting underwriting discounts and commissions and estimated deferred offering costs Deferred, direct offering costs are capitalized and consist of fees and expenses incurred in connection with the sale of our common stock in an IPO, including the legal, accounting, printing and other IPO-related equity plans that resulted in conjunction with the IPO in Note 22, Subsequent Events. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. The areas where significant estimates are used in the accompanying financial statements include the liability for unpaid claims, unit-based compensation, the valuation and related impairment recognition of long-lived assets, including intangibles and goodwill, and the valuation of embedded derivatives and redeemable investor units. Actual results could differ from those estimates. In accordance with its policy, the Company reviews its estimated liability for unpaid claims on an ongoing basis. During the second quarter of 2020, this review indicated that actual medical claims expense was higher than prior period estimates due to a change in our historical payer claim receipt and payment patterns. As a result, as of the period ended June 30, 2020, the Company updated its estimate of its liability of unpaid claims, primarily based on historical experience of medical claims expense. The result of this updated information was additional medical claims expense for the three-months ended June 30, 2020 of approximately $4,599, or $(8.55) per unit (basic and diluted) related to the first quarter of 2020 and $11,344 related to the year ended December 31, 2019, or $(21.10) per unit (basic and diluted). Additionally, for the six-months ended June 30, it resulted in incremental medical claims expense of approximately $11,344 related to the year ended December 31, 2019, or $(19.60) per unit (basic and diluted). Business Combination On April 2, 2019, the Company entered into an agreement to purchase a primary care center, which constitutes a business, located in Flint, Michigan for cash consideration of $166, which was accounted for under the acquisition method of accounting pursuant to ASC 805. The acquisition is not material to the consolidated financial statements. Impact of COVID-19 On March 11, 2020, the World Health Organization designated COVID-19 COVID-19 COVID-19 non-emergent re-imposing COVID-19 In response to the COVID-19 six-months • Created a COVID-19 • Temporarily closed all of our corporate offices and enabled our entire corporate work force to work remotely; • Implemented travel restrictions for non-essential • Transitioned much of our center-based care to be delivered by our providers virtually through newly developed telehealth capabilities, including video and telephone; • Made operational changes to the staffing and operations of our centers, which remain open as “essential” businesses, to minimize potential exposure to and transmission of COVID-19; • Temporarily delayed planned openings of new centers; • Temporarily halted community outreach and other marketing initiatives which drive new patients to our platform; • Acquired and deployed significantly greater amounts of personal protective equipment (“PPE”) to ensure the safety of our employees and patients; • Created a program called “COVID Care” to actively monitor our patients for suspected COVID-19 • Redeployed our contracted and employed drivers, who typically transport patients to our centers, to deliver food from food pantries to our patients to address food supply issues or challenges. The COVID-19 six-months per-patient-per-month We do expect COVID-19 at-risk COVID-19 pre-COVID-19 COVID-19 COVID-19, at-risk COVID-19 COVID-19 On March 27, 2020, the United States President signed into law the Coronavirus Aid, Relief and Economic Securities Act (“CARES Act”) which provides economic assistance to a wide array of industries, including healthcare. Thus far, the Company has taken the following actions related to this legislation: • Provider COVID-19 COVID-19 COVID-19. During the three and six-months end ed J 30 , COVID-19 The remainin g $3,914 was included in other current liab i lities at u ne 30, 2020 . • Medicare Accelerated and Advanced Payment Program. Through the second quarter of were in other l abi lities at June 30, 2 020 fee-for-service • Payroll Tax Deferral. One-half was - at June 30, 2020 . • Temporary Suspension of Medicare Sequestration COVID-19, increa sed b for t he three and six-months ended June 30, 2020 .

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
Significant Accounting Policies [Line Items]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Accounting The balance sheet is presented in accordance with accounting principles generally accepted in the United States of America. Separate statements of operations, comprehensive income, changes in stockholder’s equity and cash flows have not been presented because there have been no activities in this entity as of June 30, 2020.
OAK Street Health L L C And Affiliates [Member]
Significant Accounting Policies [Line Items]
Summary of Significant Accounting Policies	NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The Company described three and six-month COVID-19 Recently Adopted Accounting Pronouncements In July 2018, the FASB issued ASU 2018-09, Codification Improvements 2018-09”), 2018-09 470-50, Debt Modifications and Extinguishments 718-40, Compensation-Stock Compensation-Income Taxes 2018-09, In August 2018, the FASB issued ASC 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure for Fair Value Measurement 2018-13”), 2018-13 Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, Leases 2016-02”), right-of-use 2016-02 2020-05 2016-02 2016-02 2016-02, In July 2017, the FASB issued ASU 2017-11, Earnings Per Unit Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception 2017-11”). 2017-11 2017-11 2017-11 In October 2018, the FASB issued ASU 2018-17, Consolidation – Targeted Improvements to Related Party Guidance for Variable Interest Entities (Topic 810) 2018-17”). 2018-17 2018-17 2018-17 2018-17 In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting 2018-07”) Revenue from Contracts with Customers In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments 2016-13”). 2016-13 off-balance 2016-13 In January 2020, the FASB issued ASU 2020-01, Investments—Equity Securities (Topic 321), Investments—Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815)—Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 (“ASU 2020-01”). 2020-01 2020-01 We do not expect that any other recently issued accounting guidance will have a significant effect on our consolidated financial statements.

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2020
Stockholders' Equity Note [Abstract]
Common Stock	3. Common Stock The Company was no of which was issued or outstanding as of June 30, 2020. In connection with the Company’s IPO described in Note 4, the Company increased its authorized shares in August 2020.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Revenue Recognition [Line Items]
Revenue Recognition	NOTE 3. REVENUE RECOGNITION Both our capitated and fee-for-service Capitated Revenue and Accounts Receivable Capitated revenue consists primarily of capitated fees for medical services provided by us under capitated arrangements directly made with various Medicare Advantage managed care payors. The Company receives a fixed fee per patient under what is typically known as a “risk contract.” Risk contracting, or full risk capitation, refers to a model in which the Company receives from the third-party payor a fixed payment per patient per month (“PPPM” payment) for a defined patient population, and the Company is then responsible for providing healthcare services required by that patient population. The Company is responsible for incurring or paying for the cost of healthcare services required by that patient population in addition to those provided by the Company. Fees are recorded gross in revenues because the Company is acting as a principal in arranging for, providing and controlling the managed healthcare services provided to the managed care payors’ eligible enrolled members. Neither the Company n The Company’s payor contracts generally have a term of one year or longer, but the contracts between the enrolled members (our customers) and the payor are one calendar year or less. In general, the Company considers all contracts with customers (enrolled members) as a single performance obligation to stand ready to provide managed healthcare services. The Company identified that contracts with customers for capitation arrangements have similar performance obligations and therefore groups them into one portfolio. This performance obligation is satisfied as the Company stands ready to fulfill its obligation to enrolled members. Our revenues are based upon the estimated PPPM amounts we expect to be entitled to receive from Medicare Advantage managed care payors. The PPPM rates are determined as a percent of the premium the Medicare Advantage plan receives from CMS for our at-risk six-months three and six-months 3 606-10-32-18 Certain third-party payor contracts include a Medicare Part D payment related to pharmacy claims, which is subject to risk sharing through accepted risk corridor provisions. Under certain agreements the fund risk allocation is established where the Company, as the contracted provider, receives only a portion of the risk and the associated surplus or deficit. The Company estimates and recognizes an adjustment to Part D capitated revenues related to these risk corridor provisions, based upon pharmacy claims experience to date, as if the annual risk contract were to terminate at the end of the reporting period. Medicare Part D comprised 2% of capitated revenues and 3% of medical claims expense for the three and six-months six-months The Company had agreements in place with the payors listed below and payor sources of capitated revenue for each period presented were as follows: Three-Months Ended June 30, 2020 2019 Humana 47 % 62 % Wellcare 11 % 9 % Cigna-HealthSpring 11 % 9 % Other 31 % 20 % Six-Months Ended June 30, 2020 2019 Humana 48 % 63 % Wellcare 11 % 9 % Cigna-HealthSpring 11 % 9 % Other 30 % 19 % Other Patient Service Revenue Other patient service revenue is comprised of ancillary fees earned under contracts with certain managed care organizations for the provision of certain care coordination services and care management services and is also comprised of fee-for-service Three-Months Ended June 30, 2020 2019 Care coordination and care management services $ 5,217 $ 1,873 Fee-for-service 1,168 1,561 Total other patient services revenue $ 6,385 $ 3,434 Six-Months Ended June 30, 2020 2019 Care coordination and care management services $ 9,276 $ 2,456 Fee-for-service 2,304 3,026 Total other patient services revenue $ 11,580 $ 5,482 The Company has entered into multi-year agreements with Humana and its affiliates to provide services at certain centers to members covered by Humana. The agreements contain an administrative payment from Humana in exchange for the Company providing certain care coordination services during the term of the contract (“Care Coordination Payment”). The C C P pro-rata Care management services are provided to enrolled members of certain contracted managed care organizations regardless of whether those members are Oak Street Health patients. Similar to the other care management services provided to the Company’s centers, the Company provides delegated services and other administrative services to plans in order to assist with the management of its Medicare population, therefore, we have identified a single performance obligation to stand ready to provide care management services, which constitutes a series of distinct service increments. Fee-for-service Company Fee-for-service Three-Months Ended June 30, 2020 2019 Medicare 54 % 46 % Humana 6 % 14 % Other 40 % 40 % Six-Months Ended June 30, 2020 2019 Medicare 49 % 46 % Humana 8 % 14 % Other 43 % 40 % Other patient service accounts receivable consists primarily of amount due from Medicare and Medicare Advantage plans for fee-for-service The Company has a financial assistance policy in which patients will be assessed for financial hardship and other criteria that are used to make a good-faith determination of financial need, in which case the Company will waive or reduce a Medicare beneficiary’s obligation to pay copay, coinsurance or deductible amounts owed for the provision of medical services. The majority of our fee-for-service six-months six-months cost-to-charge fee-for-service fee-for-service Remaining Performance Obligations As our performance obligations relate to contracts with a duration of one year or less, the Company elected the optional exemption in ASC 606-10-50-14(a).

Fair value of Financial Instrum

Fair value of Financial Instruments	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Fair Value of Financial Instruments [Line Items]
Fair value of Financial Instruments	NOTE 4. FAIR VALUE OF FINANCIAL INSTRUMENTS In accordance with ASC 820, Fair Value Measurements and Disclosures Assets and liabilities carried at fair value are required to be classified and disclosed in one of the following three categories: Level 1 Quoted market prices in active markets for identical assets or liabilities. Level 2 Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3 Unobservable inputs that are not corroborated by market data. When determining the fair value measurements for assets and liabilities required to be recorded at fair value, management considers the principal or most advantageous market in which it would transact and considers risks, restrictions, or other assumptions that market participants would use when pricing the asset or liability. The carrying amounts of financial instruments including cash, accounts receivable, accounts payable, accrued liabilities and short-term borrowings approximate fair value due to the short maturity of these instruments. The bifurcated derivative associated with the long-term debt (see Note 10) was was were six-month See Note 22, Subsequent Events, for further discussion around the prepayment made on the Company’s debt and related expense (including the bifuricated derivative) recorded as result of the extinguishment of debt in conjunction with the IPO.

Property And Equipment

Property And Equipment	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Property, Plant and Equipment [Line Items]
Property And Equipment	NOTE 5. PROPERTY AND EQUIPMENT Property and equipment consisted of the following as of June 30, 2020 and December 31, 2019: June 30, December 31, Leasehold improvements $ 57,686 $ 56,608 Furniture and fixtures 4,528 3,888 Computer equipment 12,916 9,785 Internal use software 3,088 1,679 Office equipment 9,308 8,934 Construction in process 4,648 3,212 Total property and equipment, at cost 92,174 84,106 Less accumulated depreciation (21,695 ) (16,710 ) Property and equipment, net $ 70,479 $ 67,396 The Company recorded depreciation expense of $2,577 and $1,760 for the three-months ended June 30, 2020 and 2019, respectively, and $4,985 and $3,388 for the six-months

Goodwill And Intangible Assets

Goodwill And Intangible Assets	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Goodwill and Intangible Assets [Line Items]
Goodwill And Intangible Assets	NOTE 6. GOODWILL AND INTANGIBLE ASSETS Goodwill, which represents the excess of cost over the fair value of net assets acquired, amounted to $9,634 at June 30, 2020 and December 31, 2019. Pursuant to ASC 350, “Intangibles – Goodwill and Other,” we review the recoverability of goodwill annually as of October 1 or whenever significant events or changes occur which might impair the recovery of recorded amounts. For purposes of the annual goodwill impairment assessment, the Company has identified a single reporting unit. The most recently completed impairment test of goodwill was performed as of October 1, 2019, and it was determined that no impairment existed. No other indicators of impairment were identified during the year. Intangible assets with a finite useful life continue to be amortized over its useful lives. Net intangible assets amounted to $3,159 and $3,352 at June 30, 2020 and December 31, 2019, respectively. The Company recorded amortization expense of $97 for the three-months ended June 30, 2020 and 2019, and $193 for the six-months Due to the COVID-19 was III-E) COVID-19 Our Significant Accounting Policy for goodwill and intangibles assets were COVID-19

Internal Use Software

Internal Use Software	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Internal Use Software [Line Items]
Internal Use Software	NOTE 7. INTERNAL USE SOFTWARE Canopy is an application that was created by the Company’s internal Information Technology team in 2017 to provide support for Greenway, its electronic medical records (“EMR”) software. The Company’s EMR collects and contains general information such as treatment and medical history about its patients. The Canopy application is used to help fill Greenway gaps and make way for innovative healthcare tools. The Company considers the application as internal use as the Company does not market or sell the software. The Company capitalizes certain costs related to the development of Canopy. Costs incurred during the application development phase are capitalized only when the Company believes it is probable the development will result in new or additional functionality. The types of costs capitalized during the application development phase include employee compensation, as well as consulting fees for third-party developers working on these projects. Costs related to the preliminary project stage and post implementation activities are expensed as incurred. Internal use software is amortized on a straight-line basis over the estimated five-year life of the asset. As of June 30, 2020 and December 31, 2019, the Company capitalized a total of $3,088 and $1,679 of internal use software and recorded $469 and $327 in accumulated depreciation, respectively. The Company expensed $78 and $32 of capitalized development costs for the three-month periods ended June 30, 2020 and 2019, respectively, and $141 and $62 for the six-month

Other Current And Long-Term Lia

Other Current And Long-Term Liabilities	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Other Liabilities [Line Items]
Other Current And Long Term Liabilities Disclosure	NOTE 8. OTHER CURRENT AND LONG-TERM LIABILITIES Accrued compensation and benefits consisted of the following as of: June 30, 2020 December 31, Accrued paid time off $ 4,427 $ 2,319 Accrued bonus and commission 9,197 16,814 Accrued payroll and taxes 6,558 7,052 Other 2,437 2,425 Total $ 22,619 $ 28,610 Other current liabilities consisted of the following as of: June 30, 2020 December 31, Humana license fee $ 3,339 $ 2,753 Lease incentive obligation, current 550 550 Contract liabilities, current 3,107 3,785 Accrual for goods or services received, not invoiced 3,067 2,876 CARES Act stimulus payments 5,434 — Other current liabilities 1,581 1,037 Total $ 17,078 $ 11,001 Other long-term liabilities consisted of the following as of: June 30, 2020 December 31, Contract liabilities, net of current $ 6,371 $ 5,039 Lease incentive obligation, net of current 5,330 5,605 Bifurcated derivative 449 152 CARES Act deferred payroll taxes 1,800 — Other long-term liabilities 20 20 Total $ 13,970 $ 10,816

Liability For Unpaid Claims

Liability For Unpaid Claims	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Disclosure Of Liability For Unpaid Claims	NOTE 9. LIABILITY FOR UNPAID CLAIMS Medical claims expense and the liability for unpaid claims include estimates of the Company’s obligations for medical care services that have been rendered by third parties on behalf of insured consumers for which the Company is contractually obligated to pay (through the Company’s full risk capitation arrangements), but for which claims have either not yet been received, processed, or paid. The Company develops estimates for medical care services incurred but not reported (“IBNR”), which includes estimates for claims that have not been received or fully processed, using a process that is consistently applied, centrally controlled and automated. This process includes utilizing actuarial models when a sufficient amount of medical claims history is available from the third-party healthcare service providers. The actuarial models consider factors such as time from date of service to claim processing, seasonal variances in medical care consumption, health care professional contract rate changes, medical care utilization and other medical cost trends, membership volume and demographics, the introduction of new technologies, benefit plan changes, and business mix changes related to products, customers and geography. In developing its unpaid claims liability estimates, the Company applies different estimation methods depending on which incurred claims are being estimated. For the most recent three months, the Company estimates claim costs incurred by applying observed medical cost trend factors to the average PPPM medical costs incurred in prior months for which more complete claims data are available, supplemented by a review of near-term completion factors (actuarial estimates, based upon historical experience and analysis of current trends, of the percentage of incurred claims during a given period that have been adjudicated by the Company at the date of estimation). For the months prior to the most recent three months, the Company applies completion factors to actual claims adjudicated-to-date The Company purchases provider excess insurance to protect against significant, catastrophic claims expenses incurred on behalf of its patients. The total amount of provider excess insurance premium was $869 and $448, and total reimbursements were $446 and $0 for the three-month periods ended June 30, 2020 and 2019, respectively. The total amount of provider excess insurance premium was $1,712 and $958, and total reimbursements were $752 and $0 for the six-month The Company’s liabilities for unpaid claims were June 30, 2020 December 31, Balance, beginning of period $ 170,629 $ 68,174 Incurred health care costs (third-party medical claims expense and administrative health plan fees): Current period 274,687 383,169 Prior period 11,344 268 Total claims incurred 286,031 383,437 Third-party medical claims and administrative health plan fees paid: Current period (160,973 ) (226,618 ) Prior period (59,643 ) (56,220 ) Total claims paid (220,616 ) (282,838 ) Adjustment to other claims-related liabilities (188 ) 1,856 Balance, end of period $ 235,856 $ 170,629 We assess the profitability of our managed care capitation arrangement to identify contracts where current operating results or forecasts indicate probable future losses. If anticipated future variable costs exceed anticipated future revenues, a premium deficiency reserve is recognized. No premium deficiency reserves were recorded as of June 30, 2020 and December 31, 2019. In accordance with its policy, the Company reviews its estimated liability for unpaid claims on an ongoing basis. During the second quarter of 2020, this review indicated that actual medical claims expense was higher than prior period estimates as well as a change in our historical payer claim receipt and payment patterns. As a result, as of the period ended June 30, 2020, the Company updated its estimate of its liability of unpaid claims, primarily based on historical experience of medical claims expense. The result of this updated information was additional medical claims expense for the three-months ended June 30, 2020 of approximately $4,599, or $(8.55) per unit (basic and diluted) related to the first quarter of 2020 and $11,344 related to the year ended December 31, 2019, or $(21.10) per unit (basic and diluted). Additionally, for the six-months ended June 30, 2020, it resulted in incremental medical claims expense of approximately $11,344 related to the year ended December 31, 2019, or $(19.60) per unit (basic and diluted).

Long- Term Debt

Long- Term Debt	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Long- Term Debt	NOTE 10. LONG-TERM DEBT Long-term debt balances as of the June 30, 2020 and December 31, 2019 wer June 30, 2020 December 31, 2019 Note payable to Hercules Capital, Inc., originally dated August 7, 2017 and amended April 26, 2019 and January 13, 2020. The note bears a floating interest rate of the greater of 9.75% or the sum of the Prime Rate plus 5.00%. $ 80,000 $ 80,000 Plus: Unamortized discount and debt issuance costs 2,126 1,347 Less: Current maturities — (18,507 ) Total long-term debt $ 82,126 $ 62,840 The Company entered into a debt agreement with Hercules for $20,000 on August 7, 2017. See further discussion of the prepayment that occurred on this loan in conjunction with the IPO in Note 22, Subsequent Events. The note bears a floating interest rate of the greater of 9.75% or the sum of i) 9.75%, plus ii) the Prime Rate minus 4.75%. The interest rate at June 30, 2020 and December 31, 2019 was 9.75% and 9.75%, respectively. The note allowed for an additional $10,000 advance subject to terms and conditions of the loan agreement, which was drawn by the Company on June 28, 2018. The Company may prepay all, but not less than all, of the entire principal balance prior to maturity with an associated prepayment charge of detailed in the loan agreement. The terms of the loan agreement specify the prepayment penalty ranges from 3% to 1% depending on when prepayment occurs in relation to maturity date: if amounts are prepaid within 12 months of the Closing Date (3.0%); after 12 months but prior to 24 months (2.0%); and any time after 24 months (1.0%). The note is secured by a perfected first position lien on all of Company’s assets. The original Hercules note required 13 months of interest-only payments, followed by monthly installments on a 36-month end-of-term In April 2019, the Company amended the debt agreement with Hercules to allow for additional tranches which may be drawn upon. Tranche I is the existing loan of $30,000, Tranche II is an additional $30,000 available on April 26, 2019, Tranche III is an additional $20,000 available from July 1, 2019 through December 31, 2019 subject to continued covenant compliance, and Tranche IV is an additional $10,000 available from July 1, 2019 through December 31, 2020 subject to future lender investment committee approval. The Company received Tranche II in April 2019 and Tranche III in November 2019 but has not made any further draws. As of the date of the receipt of Tranches II and III, the maturity date of the debt agreement was amended to June 1, 2022, and further extensions of the maturity date occur upon the draw of additional tranches. In addition, upon the draw of each tranche a 5.95% end-of-term In January 2020, the Company amended the debt agreement with Hercules to provide for the following changes subject to certain performance milestones which were met in February 2020: (i) the extension of the principle payment start date from July 1, 2020 to October 1, 2021, (ii) the extension of the loan maturity date from June 1, 2022 to December 1, 2022, (iii) the change in interest rate to the greater of either 9.75% or the sum of the prime rate plus 5.00%, (iv) the change in prepayment charge to 2.0% of the amount prepaid if amounts are prepaid prior to June 30, 2020; 1% if prepaid after June 30, 2020 but on or prior to December 31, 2020; and 0.5% if prepaid thereafter prior to maturity, and (v) the elimination of all financial covenants with the exception of the net patient-level contribution covenant. The Company recorded a derivative liability related to the change in control provisions within the Hercules debt agreement in the amount of $449 and $152 as of June 30, 2020 and D e six-month The estimated fair value of the Company’s bifurcated derivative instrument has been valued using an outcome-probability-weighted discounted cash flow analysis at the end of each reporting period using inputs that are not corroborated by market data which resulted in the Company classifying such derivatives as Level 3 (see Note 4). The carrying amount of long-term debt approximates fair value because the interest rates fluctuate with market interest rates or the fixed rates are based on current rates offered to the Company for debt with similar terms and maturities. Scheduled maturity requirements of long-term debt, excluding the unamortized discount, end of term charge, and debt issuance costs as of June 30, 2020 are as follows: June 30, 2020 2020 $ — 2021 15,212 2022 64,788 Total $ 80,000 Debt issuance costs and original issuance discount As part of entering into the Hercules debt agreement, the Company incurred (or will incur due to the end-of-term June 30, 2020 December 31, 2019 Accretion of end-of-term $ (2,514 ) $ (1,830 ) Original issuance discount 191 191 Additional issuance discount 543 543 Amortization (346 ) (251 ) Unamortized discount and debt issuance costs, net $ (2,126 ) $ (1,347 ) Debt issuance costs are presented in the consolidated balance sheets as a direct deduction from the carrying value of the long-term debt. Included in debt issuance costs is an end-of-term end-of-term end-of-term

Income Tax

Income Tax	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Income Tax	NOTE 11. INCOME TAX The most significant impact to the Company’s effective tax rate is related to the tax treatment of certain equity compensation. However, the Company wa

Redeemable Investor Units

Redeemable Investor Units	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Temporary Equity [Line Items]
Redeemable Investor Units	NOTE 12. REDEEMABLE INVESTOR UNITS The membership interests of the Company non-voting The Unit III class is further divided into five series: Investor Units III-A, Investor Units III-B, Investor Units III-C, Investor Units III-D, and Investor III-E. III-B Redeemable Investor Units consist ed June 30, 2020 Units Issued Issuance Total Investor Units I 382,572 $ 12.00 $ 4,591 Investor Units II 509,796 16.20 8,259 Investor Units III-A 1,872,409 20.25 37,916 Investor Units III-A 6,043,421 26.38 159,425 Investor Units III-B 568,613 26.38 15,000 Investor Units III-C 747,661 58.78 43,948 Investor Units III-D 876,147 58.78 51,500 Investor Units III-E 1,471,623 156.29 230,000 Total 12,472,242 $ 550,639 December 31, 2019 Units Issued Issuance Total Investor Units I 382,572 $ 12.00 $ 4,591 Investor Units II 509,796 16.20 8,259 Investor Units III-A 1,872,409 20.25 37,916 Investor Units III-A 6,043,421 26.38 159,425 Investor Units III-B 568,613 26.38 15,000 Investor Units III-C 747,661 58.78 43,948 Investor Units III-D 876,147 58.78 51,500 Total 11,000,619 $ 320,639 The following table shows the Company’s activity related to its Investor Units as of and for the periods ending: Investor Investor Investor III-A Investor III-B Investor III-C Investor III-D Investor III-E Total Outstanding, December 31, 2018 382,572 509,796 7,915,830 568,613 747,661 850,629 — 10,975,101 Issued — — — — — 25,518 — 25,518 Outstanding, December 31, 2019 382,572 509,796 7,915,830 568,613 747,661 876,147 — 11,000,619 Issued — — — — — — 1,471,623 1,471,623 Outstanding, June 30, 2020 382,572 509,796 7,915,830 568,613 747,661 876,147 1,471,623 12,472,242 In May 2019, we issued 25,518 units of Investor Units III-D In February 2020, we issued 1,471,623 units of Investor Units III-E The redeemable Investor Units have the following rights and characteristics: Dividends Dividends are payable in cash, if declared, by the Company’s Board or upon a liquidation, deemed liquidation event or as determined by the Board in its sole discretion. The Company has not declared dividends for the periods ended June 30, 2020 and 2019, respectively. Preferred Return Whether or not declared or approved by the Board, the holders of the Investor Units accrue a preferred return in the amount of 8%, per annum, on the varying balance of each Investor Units’ unreturned capital contribution beginning on the date of initial investment. This preferred return is cumulative and shall take into account, in determining the satisfaction of the preferred return, all distributions resulting from or paid to members holding Investor Units in connection with a dissolution or deemed liquidation event. The following table shows accumulated dividends on the redeemable Investor Units on a cumulative basis as of the periods ended: June 30, 2020 December 31, 2019 Units Per Total Units Per Total Series Investor Units I 382,572 $ 8.36 $ 3,200 382,572 $ 7.60 $ 2,908 Investor Units II 509,796 9.93 5,063 509,796 8.95 4,563 Investor Units III-A 1,872,409 10.23 19,163 1,872,409 9.09 17,020 Investor Units III-A 6,043,421 7.62 46,037 6,043,421 6.34 38,322 Investor Units III-B 568,613 5.24 2,981 568,613 4.06 2,306 Investor Units III-C 747,661 10.76 8,041 747,661 8.14 6,089 Investor Units III-D 876,147 8.41 7,372 876,147 5.89 5,162 Investor Units III-E 1,471,623 4.29 6,315 — — — Total $ 98,172 $ 76,370 Conversion While the Company’s Investor Units have no conversion rights related to any of the Investor Unit classes, in response to a Reorganization Plan to convert the Company into a corporate form (as defined in the Oak Street Health LLC Amended and Restated Operating Agreement), Investor Unit holders are eligible to receive capital stock of the successor corporation in number of and with terms relatively consistent to their Investor Units, as ultimately determined by the Company’s Board of Directors. Redemption The Company’s Investor Units have no mandatory redemption provisions. The Investor Units are redeemable upon a Deemed Liquidation Event, and the Company determined that it does not fully control the effectuation or consummation of events that would be considered a Deemed Liquidation Event. This is because: (i) the Company’s Board of Directors are required to approve such a transaction, and (ii) the Investor Unit holders are collectively entitled to elect 5 of the 8 Board Members which gives them a majority of the Board of Directors, giving the Investor Unit holders effective control of the Board of Directors. Therefore, the Investor Units are required to be presented outside of permanent equity as mezzanine equity on the Company’s consolidated balance sheets. The Company has evaluated whether any of the potential Deemed Liquidation Events are probable of occurring and has concluded that it is not probable that the Investor Units will become redeemable, and that no subsequent measurement is required. Liquidation In the event of a liquidation, dissolution, or winding up of the Company, the holders of each of the various types of Investor Units will receive liquidation preference, prior and in preference to any distribution of any of the assets or surplus funds of the Company to the holders of Founders’ Units, equal to the greater of (i) the applicable liquidation preference (the applicable liquidation preference is described in the Fifth Amended and Restated Limited Liability Company Operating Agreement) or (ii) the amount the holders of the Investor Units would receive if such holders had converted their units into Founders’ Units immediately prior to such liquidation event. Voting Rights Founders’ Units and Investor Units, specifically excluding the Investor Units III-B,

Members' Deficit

Members' Deficit	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Members' Deficit	NOTE 13. MEMBERS’ DEFICIT Common Units The Company’s common units consist ed Founders’ Incentive Profits Total Outstanding, December 31, 2018 606,313 13,755 1,454,148 2,074,216 Granted — — 496,763 496,763 Repurchased/Forfeited — — (40,115 ) (40,115 ) Outstanding, December 31, 2019 606,313 13,755 1,910,796 2,530,864 Granted — — 1,095,067 1,095,067 Repurchased/Forfeited — — (33,320 ) (33,320 ) Tender Offer (107,208 ) (1,142 ) (22,801 ) (131,151 ) Outstanding June 30, 2020 499,105 12,613 2,949,742 3,461,460 Tender Offer Upon the Company’s Board of Directors’ approval, the Company issued a Tender Offer to Purchase for cash dated March 30, 2020 (the “Tender Offer”) which expired on April 27, 2020 up to $20,000 of eligible units at a purchase price of $156.29 per eligible unit. Founders’ Units, Incentive Units, and Profits Interests that we wa On April 27, 2020, the Company purchased all eligible units, other than Profits Interests subject to a hurdle value, at a price of $156.29 per eligible unit net to the sellers in cash, without interest. The Company purchased Profits Interests that had a hurdle value at a price for each Profits Interests equal to the excess of $156.29 over the per Profits Interests amount of that hurdle value net to the sellers in cash, without interest. The purchase price offered in the Tender Offer for eligible units was the same for all classes of eligible units (other than Profits Interests, for which the purchase price was adjusted to reflect the applicable hurdle value), even though their relative priorities in distributions may differ. The following units were tendered to the Company: Type of Units Number of Purchase Total Founders’ Units 107,208 $ 156.29 $ 16,756 Incentive Units 1,142 156.29 178 Profits Interest Hurdle Value $265,158 17,622 136.04 2,397 Profits Interest Hurdle Value $346,107 3,684 129.91 479 Profits Interest Hurdle Value $386,277 1,495 126.90 190 Total Common Units 131,151 20,000 The Units (including Profits Interests) w ere any Accumulated Deficit.

Unit-Based Compensation

Unit-Based Compensation	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Unit Based Compensation	NOTE 14. UNIT-BASED COMPENSATION Incentive Units Options In 2013, the Company’s Board adopted an equity incentive plan, subsequently replaced by the Equity Incentive Plan in 2015, in which the Company has granted awards in the form of Incentive Units options to employees, officers, directors, consultants, and other service providers of the Company. During the period ended June 30, 2020 and December 31, 2019, no Incentive Units options were exercised and 2,000 options remained outstanding at the end of the period. The options outstanding have a per unit exercise price of $12.00. Profits Interests In 2015, the Company’s Board adopted the Equity Incentive Plan (the “Equity Incentive Plan”). Under the Equity Incentive Plan, the Company has granted awards in the form of Profits Interests to employees, officers, and directors. As of June 30 During the three and six-months ed The Profits Interests awards generally vest either over a requisite service period or are contingent upon a performance condition. The Company granted 829,567 and 244,120 Profits Interests awards during the three-months ended June 30, 2020 and 2019, respectively, and 1,095,067 and 244,120 Profits Interests awards during the six-months Each Profits Interests award contains the following material terms: (i) The Profits Interests receive distributions (other than tax distributions) only upon a liquidity event, as defined, that exceeds a threshold equivalent to the fair value of the Company, as determined by the Company’s Board of Directors, at the grant date. (ii) A portion of the awards vest over a period of continuous employment or service (“Service-Vesting Units”) while the other portion of the awards only vest in the event of the Sponsor’s Exit (“Performance-Vesting Units”), as defined by the Equity Incentive Plan. The Service-Vesting Units provide for accelerated vesting upon Sponsor’s Exit should the participant’s employment be terminated (other than for cause) after the Sponsor’s Exit, but prior to the final service vesting date. (iii) All awards include a repurchase option at the election of the Company for the vested portion upon termination of employment or service. Profits Interests are accounted for as equity using the fair value method, which requires the measurement and recognition of compensation expense for all profit interest-based payment awards made to the Company’s employees based upon the grant-date fair value. The Company has concluded that both the Service-Vesting Units and the Performance-Vesting Units are subject to a market condition, and has assessed the market condition as part of its determination of the grant date fair value. For Performance-Vesting Units, the Company recognizes unit-based compensation expense when it is probable that the performance condition will be achieved. The Company will analyze if a performance condition is probable for each reporting period through the settlement date for awards subject to performance vesting. For Service-Vesting Units, the Company recognizes unit-based compensation expense over the requisite service period for each separately vesting portion of the profits interest as if the award was, in-substance, Accordingly, the Company determined the fair value of each award on the date of grant using both the income and market approaches, including the backsolve method with the following assumptions used for grants issued for the three and six-months Six-Months Ended June 30, 2020 2019 Risk-Free Rate .16 % 1.58 % Volatility 65.0 % 35.0 % Time to Liquidity Event (Years) 2.00 2.19 The volatility assumption used in the weighted-average income and market approaches is based on the expected volatility of public companies in similar industries, adjusted to reflect the differences between the Company and public companies in size, resources, time in industry, and breadth of product and service offerings. Expected dividend yield was assumed to be zero given the Company’s history of declaring dividends and the Company’s lack of intent to pay dividends in the foreseeable future. The following is a summary of Profits Interests award transactions as well as the Profits Interests outstanding and their corresponding hurdle values as of and for the periods ended June 30, 2020 and December 31, 2019: Profits Interests Weighted-Average Outstanding, December 31, 2018 1,454,148 2.35 Granted 496,763 42.35 Vested 193,375 2.32 Forfeited/Repurchased (40,115 ) 5.74 Outstanding, December 31, 2019 1,910,796 12.68 Granted 1,095,067 53.51 Vested 188,381 5.09 Forfeited/Repurchased (56,121 ) 10.01 Outstanding, June 30, 2020 2,949,742 11.32 Vested outstanding, June 30, 2020 550,698 Vested outstanding, December 31, 2019 389,531 As of June 30, 2020 As of December 31, 2019 Units Outstanding Hurdle Value Units Hurdle 93,455 $ 265,158 111,076 $ 234,834 151,370 346,107 160,492 306,706 43,780 386,277 45,275 342,451 253,874 685,350 265,374 608,955 510,450 782,361 462,292 645,000 458,090 922,500 521,225 697,700 343,656 1,582,500 345,062 1,310,000 380,250 2,200,000 — — 714,817 2,210,000 — — Total 2,949,742 Total 1,910,796 The Company recognized $3,502 and $543 in unit-based compensation expense related to the Profits Interests for the three-month periods ended June 30, 2020 and 2019, respectively, and $5,380 and $799 for the six-month we d non-vested d

Commitments - Litigation And Co

Commitments - Litigation And Contingencies	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Commitments Litigation And Contingencies	NOTE 15. COMMITMENTS – LITIGATION AND CONTINGENCIES Contingencies The Company is presently, and from time to time, subject to various claims and lawsuits arising in the normal course of business. In the opinion of management, the ultimate resolution of these matters will not have a material adverse effect on the Company’s financial position or results of operations. Uncertainties The healthcare industry is subject to numerous laws and regulations of federal, state and local governments. These laws and regulations include, but are not limited to, matters such as licensure, accreditation, Government healthcare program participation requirements, reimbursement for patient services, and Medicare and Medicaid fraud and abuse. Recently, government activity has increased with respect to investigations and allegations concerning possible violations of fraud and abuse statues and regulations by healthcare providers. Violations of these laws and regulations could result in expulsion from government healthcare programs together with imposition of significant fines and penalties, as well as significant repayments for patient services billed. Management believes that the Company is in compliance with fraud and abuse as well as other applicable government laws and regulations. While no regulatory inquiries have been made, compliance with such laws and regulations is subject to government review and interpretation, as well as regulatory actions unknown at this time.

Commitments - Operating Leases

Commitments - Operating Leases	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Commitments Operating Leases	NOTE 16. COMMITMENTS – OPERATING LEASES The Company leases corporate office space and operating facilities under operating leases. The Company’s headquarters is located in Chicago, Illinois. The Company recognized $4,608 and $2,765 of rent expense for the three-month periods ended June 30, 2020 and 2019 respectively, and $9,221 and $5,444 for the six-month Various lease agreements provide for escalating rent payments over the life of the respective lease and the Company recognizes rent expense on a straight-line basis over the life of the lease. This results in a non-interest-bearing wa In addition to base rent, the centers are generally responsible for their proportionate share of real estate taxes and common area charges. Most of the leases contain renewal options at the Company’s election whereby the lease could be extended for terms ranging from five to ten years with base rent escalations.

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Variable Interest Entities	NOTE 17. VARIABLE INTEREST ENTITIES The Physician Groups (as defined in Note 1) were established to employ healthcare providers, contract with managed care payors, and to deliver healthcare services to patients in the markets that the Company serves. The Company evaluated whether it has a variable interest in the Physician Groups, whether the Physician Groups are VIEs, and whether the Company has a controlling financial interest in the Physician Groups. The Company concluded that it has variable interests in the Physician Groups on the basis of its Administrative Service Agreement (“ASA”) which provides for reimbursement of costs and a management fee payable to the Company from the Physician Groups in exchange for providing management and administrative services which creates risks and a potential return to the Company. The Physician Group’s equity at risk, as defined by U.S. GAAP, is insufficient to finance its activities without additional support, and, therefore, the Physician Groups are considered VIEs. In order to determine whether the Company has a controlling financial interest in the Physician Groups, and, thus, is the Physician’s primary beneficiary, the Company considered whether it has i) the power to direct the activities of Physician Groups that most significantly impact its economic performance and ii) the obligation to absorb losses of the Physician Groups that could potentially be significant to it or the right to receive benefits from Physician Groups that could potentially be significant to it. The Company concluded that the unitholders and employees of the Physician Groups are structured in a way that neither unitholder, employees nor their designees has the individual power to direct the activities of the Physician Groups that most significantly impact its economic performance. Under the ASA, MSO is responsible for providing management and administrative services related to the growth of the patient population of the Physician Groups, the management of that population’s healthcare needs, and the provision of required healthcare services to those patients. The Company has concluded that the success or failure of MSO in conducting these activities will most significantly impact the economic performance of the Physician Groups. In addition, the Company’s variable interests in the Physician Groups provide the Company with the right to receive benefits that could potentially be significant to it. The single member of the Physician Groups is a member and employee of OSH. As a result of this analysis, the Company concluded that it is the primary beneficiary of the Physician Groups and therefore consolidates the balance sheets, results of operations and cash flows of the Physician Groups. The Company performs a qualitative assessment of the Physician Groups on an ongoing basis to determine if it continues to be the primary beneficiary. The table below illustrates the VIE assets and liabilities and performance for the Physician Groups as of and for the periods ended: June 30, 2020 December 31, 2019 Total assets $ 363,307 $ 252,629 Total liabilities 301,621 230,527 Three-Months Ended June 30, 2020 2019 Total revenues $ 210,314 $ 125,215 Operating expenses: Medical claims expense 154,656 83,577 Cost of care, excluding depreciation and amortization 14,187 9,229 Total operating expenses $ 168,843 $ 92,806 Six-Months June 30, 2020 2019 Total revenues $ 408,778 $ 242,591 Operating expenses: Medical claims expense 286,032 160,271 Cost of care, excluding depreciation and amortization 29,534 17,180 Total operating expenses $ 315,566 $ 177,451 Physician Group revenues consist of amounts recognized for services provided to patients and includes capitated revenue and a portion of the Company’s other patient service revenue, and exclude certain care management services. All capitation arrangements are drafted at the Physician Group level. Operating expenses consist primarily of medical claims expense, a majority of which are third-party medical claims expenses and administrative health plan fees, and exclude fees to perform payor delegated activities and provider excess insurance costs. Cost of care, excluding depreciation and amortization primarily includes provider salaries and benefits and other clinical operating costs which are reported in cost of care, excluding depreciation and amortization in the consolidated statements of operations. These amounts do not include intercompany revenues and costs, principally management fees between MSO and the Physician Groups, which are eliminated in consolidation. There are no restrictions on the Physician Groups’ assets or on the settlement of its liabilities. The assets of the Physician Groups can be used to settle obligations of the Company. The Physician Groups are included in the Company’s obligated group; thus, creditors of the Company have recourse to the assets owned by the Physician Groups. There are no liabilities for which creditors of the Physician Groups do not have recourse to the general credit of the Company. There are no restrictions placed on the retained earnings or net income of the Physician Groups with respect to potential dividend payments.

Related Parties

Related Parties	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Related Parties	NOTE 18. RELATED PARTIES In September 2018, the Company signed an agreement issuing 850,629 of a new class of investor units (Investor Units III-D) The balance ed redeemable investor units’ d Revenues The Company also has capitated managed care contracts with Humana. Total capitated revenues related to the Humana payor contracts were $97,367 and $75,731 for the three-month periods ended June 30, 2020 and 2019, respectively, and $193,854 and $149,413 for the six-month ed fee-for-service six-month fee-for-service six-month ed fee-for-service The unearned portion of the Care Coordination Payments is recorded in both the short term and long-term other liabilities accounts. The liability related to Humana Care Coordination Payments ed liabilities’ Expenses Total medical claims expenses related to the Humana payor contracts were $63,973 and $50,771 in the three-month periods ended June 30, 2020 and 2019, respectively, and $123,818 and $99,372 in the six-month ed The Humana Alliance Provision contains an arrangement for a license fee that is payable by the Company to Humana for the Company’s provision of health care services in certain centers owned or leased by Humana. The license fee is a reimbursement to Humana for its costs of owning or leasing and maintaining the centers, including rental payments, center maintenance or repair expenses, equipment expenses, special assessments, cost of upgrades, taxes, leasehold improvements, and other expenses identified by Humana. The total license fees paid to Humana during the three-month periods ended June 30, 2020 and 2019 were $671 and $486 respectively, and the six-month ed The Company has entered into certain lease arrangements with Humana, which account ed within the cost of care line item for the three-month periods ended June 30, 2020 and 2019, respectively, and $1,063 and $661 for the six-month periods ended June 30, 2020 and 2019, respectively. The deferred rent liability related to Humana leases represent ed

Segment Financial Information

Segment Financial Information	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Segment Financial Information	NOTE 19. SEGMENT FINANCIAL INFORMATION The Company’s chief operating decision makers regularly review financial operating results on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company identifies operating segments based on the responsibility of its chief operating decision makers and operates in and reports as a single operating segment, which is to care for its patients’ needs. For the periods presented, all of the Company’s long-lived assets were located in the United States, and all revenue was earned in the United States.

Net Loss Per Unit

Net Loss Per Unit	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Net Loss Per Unit	NOTE 20. NET LOSS PER UNIT Net loss per common unit for the three-months and six-months we non-voting two-class Diluted net loss per common unit is computed by adjusting the net loss available to common unitholders and the weighted-average number of common units outstanding to give effect to potentially dilutive securities. The Company has issued potentially dilutive instruments in the form of Incentive Unit Options granted to the Company’s employees, officers, directors, and members. The Company did not include any of these instruments in its calculation of diluted loss per unit during the three-months and six-months The following table sets forth the computation of basic and diluted net loss per common unit for the three-months ended June 30: June 30, June 30, Net loss attributable to unitholders – basic and diluted: Net loss attributable to the Company $ (26,765 ) $ (20,161 ) Less: Undeclared and deemed dividends on Investor Units (12,230 ) (7,188 ) Net loss attributable to common unitholders (38,995 ) (27,349 ) Weighted average common units outstanding 537,654 620,068 Net loss attributable to common unitholders – basic and diluted $ (72.53 ) $ (44.11 ) Potentially dilutive securities excluded from the computation of diluted net loss per unit because including them would have been anti-dilutive Options to purchase Incentive Units 2,000 2,000 Profits Interests 2,949,742 1,675,091 Total 2,951,742 1,677,091 The following table sets forth the computation of basic and diluted net loss per common unit for the six-months June 30, June 30, Net loss attributable to unitholders – basic and diluted: Net loss attributable to the Company $ (41,765 ) $ (30,156 ) Less: Undeclared and deemed dividends on Investor Units (21,802 ) (14,302 ) Net loss attributable to common unitholders (63,567 ) (44,458 ) Weighted average common units outstanding 578,861 620,068 Net loss attributable to common unitholders – basic and diluted $ (109.81 ) $ (71.70 ) Potentially dilutive securities excluded from the computation of diluted net loss per unit because including them would have been Options to purchase Incentive Units 2,000 2,000 Profits Interests 2,949,742 1,675,091 Total 2,951,742 1,677,091

Pro Forma Information

Pro Forma Information	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Pro Forma Information	NOTE 21. PRO FORMA INFORMATION (UNAUDITED) The Company evaluates its legal structure from time to time to assess whether the existing legal structure is the most appropriate for our operations and owners. The following paragraphs detail the impact to our financials should we decide to convert the Company to a corporation in accordance with Subchapter C of the Internal Revenue Code (a “C” corporation). The pro forma net income taxes and pro forma net income reflect federal and state income taxes (assuming a 25% combined effective tax rate) as if the Company had been taxed as a C corporation for the periods ended June 30, 2020 and 2019. The Company determined that the pro forma net income tax expense for the periods ended June 30, 2020 and 2019 was zero, and accordingly, and pro forma net income remained unchanged from amounts as reported. Additionally, deferred income tax assets and liabilities will be recognized as a result of the conversion from a limited liability company to a C corporation. The Company is in a net deferred tax asset position. In accordance with accounting standards, the Company has recorded a valuation allowance to reduce the value of the net deferred tax assets to zero, the amount that is more likely than not to be realized. In evaluating the amount of deferred tax assets that were more likely than not to be realized the Company looked at all evidence both positive and negative in making its determination. The Company has been was

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2020
Subsequent Events	4. Subsequent Events The Company has evaluated subsequent events through September 16, 2020, the date that this financial statement was issued. Initial Public Offering On August 5, 2020, our IPO Registration Statement on Form S-1 shares of common stock, par value $0.001 per share, was declared effective by the Securities & Exchange Commission. Our common stock began trading on August 6, 2020 on the New York Stock Exchange (“NYSE”) under the ticker symbol “OSH.” As a result, our financial statements as of June 30, 2020 do not reflect the impact of the IPO. On August 10, 2020, we completed our IPO in which we issued and sold 17,968,750 shares of our common stock at an offering price of $21.00 per share. This share amount includes the exercise in full of the underwriters’ options to purchase our Deferred, direct offering costs are capitalized and consist of fees and expenses incurred in connection with the sale of our common stock in our IPO, including the legal, accounting, printing and other IPO-related Upon completion of the IPO, these deferred offering costs were reclassified to stockholders’ equity of the Company and recorded against the net proceeds from the offering . On August 10, 2020, we increased our authorized shares to 500,000,000 shares of our common stock and 50,000,000 shares of our preferred stock, par value $0.001. Conversion of Existing Equity The membership interests of OSH LLC, a wholly owned subsidiary of the Company, contain five classes of Units, consisting of voting classes of Units known as Founders’ Units (the “Founders’ Units”) and three classes of Investor Units known as Investor Units I, Investor Units II and Investor Units III (collectively with the Initial Investor Units, the “Investor Units”) and a non-voting class of Units (the “Incentive Units”). While OSH LLC’s Investor Units had In March 2018, OSH LLC’s Board of Directors approved the Amended and Restated Equity Incentive Plan (the “Incentive Plan”). The Incentive Plan states that in the occurrence of an IPO, the Board may, in its discretion, (i) cause the exchange of Incentive Units for units or shares of common stock or other equity securities and apply the vesting provisions applicable to the Incentive Units to such shares of common stock or other equity securities; (ii) adjust the number of Incentive Units issued under the Incentive Plan or under any particular award; (iii) adjust the hurdle value applicable to any Incentive Units; and/or (iv) cancel all or any portion of the Incentive Units in exchange for payment to the plan participant in cash or capital stock (or other equity interests) or any combination thereof, of the fair market value of the Incentive Units; in each case, determined by the Board in a manner generally consistent with the treatment of other Units, taking into consideration the relative rights of all Units, including the hurdle value applicable to Incentive Units. Prior to the closing of the IPO, the other direct and indirect equityholders of OSH LLC completed a series of transactions in accordance with the master structuring agreement dated as of August 10, 2020, by and among the Company and other signatories party thereto (the “Master Structuring Agreement”) that resulted in the Company becoming the ultimate parent company of OSH LLC and the current equityholders of OSH LLC immediately prior to the close of the IPO exchanged their interests (Founders Units, Investor Units, and Incentive Units) in OSH LLC for common stock of the Company as approved by the Board of Directors of the Company, OSH LLC and OSH Management Holdings, LLC (“OSH MH LLC”). We refer to these transactions as the “Organizational Transactions.” • General Atlantic LLC and Newlight Partners LP (the “Lead Sponsors”) contributed their respective interests in OSH LLC to the Company in exchange for 126,278,767 shares of common stock in the Company, pursuant to a contribution and exchange agreement dated August 10, 2020 by and among the Company and the other signatories party thereto. • OSH MH LLC, the entity through which our employees owned Founders’ of which w e also received eir Founders’ s and pr ofits interests in OSH MH LLC. • OSH LLC merged pursuant to the merger agreement dated August 10, 2020 by and among the Company, OSH LLC and the other signatory thereto (the “Company Merger”) with and into a newly formed subsidiary of the Company, with OSH LLC surviving as a wholly owned subsidiary of the Company. Pursuant to the Company Merger, the investors in OSH LLC received a total of 58,467,139 shares of common stock in the Company in exchange for their Units in OSH LLC. As a result of the abovementioned conversion of existing equity based on the provisions of the OSH LLC Amended and Restated Operating Agreement, the Company reclassified its existing redeemable preferred units and members’ capital to common stock on the Company’s balance sheet. Consolidation Upon the completion of the IPO, our sole material asset is our interest in OSH LLC and its operating subsidiaries. In accordance with the Master Structuring Agreement, we have all management powers over the business and affairs of OSH LLC and to conduct, direct and exercise full control over the activities of OSH LLC. Accordingly, following the Organizational Transactions and the effective date of the IPO, we will consolidate the financial results of OSH LLC and its subsidiaries. Oak Street Health, LLC is the Oak Street Health, Inc. predecessor for financial reporting purposes. Payoff of Long-Term Debt OSH LLC entered into a debt agreement with Hercules Capital, Inc. (“Hercules”) for $20,000 on August 7, 2017. In April 2019, OSH LLC amended the debt agreement with Hercules to allow for additional tranches which may be drawn upon. Tranche I is the existing loan of $30,000, Tranche II is an additional $30,000 available on April 26, 2019, Tranche III is an additional $20,000 available from July 1, 2019 through December 31, 2019 subject to continued covenant compliance, and Tranche IV is an additional $10,000 available from July 1, 2019 through December 31, 2019 subject to future lender investment committee approval. OSH LLC received Tranche II in April 2019 and Tranche III in November 2019 but has not made any further draws. As of the date of the receipt of Tranches II and III, the maturity date of the debt agreement was amended to June 1, 2022, and further extension of the maturity date occur upon the draw of additional tranches. In addition, upon the draw of each tranche a 5.95% end-of-term charge is applied to the total drawn amount and will be due upon the amended maturity date . On August 11, 2020, the Company used a portion of the net proceeds from the offering to pay off the $80,000 principal outstanding under the Hercules debt agreement, 9.75% interest loan originally due to mature December 2022 in full at a price of 107%. In connection with the voluntary prepayment of the entire remaining borrowings outstanding, the Company will recognize interest expense , net of $3,204 during the third quarter of 2020 related to the prepayment charge, the end of term charge and the write off of unamortized debt issuance costs. The remainder of the net proceeds from the IPO will be used for general corporate purposes. 2020 Omnibus Incentive Plan On August 5, 2020, the Company’s Board of Directors adopted the 2020 Omnibus Incentive Plan (the on August 5, 2020. Under the 2020 Plan, pursuant to which employees, consultants and directors of our company and our affiliates perform services for us, including our executive officers, are eligible to receive awards. The 2020 Plan provides for the grant of stock options, stock appreciation rights, restricted shares, performance awards, other share-based awards (including restricted stock units (“RSUs”)) and other cash-based awards. The maximum number of shares available for issuance under the 2020 Plan may not exceed 48,138,967 shares (the “Share Reserve”). The Share Reserve will automatically increase on each January 1 that occurs after the August 5, 2020 effective date, for 10 years, by an amount equal to 5% of the total number of shares outstanding on December 31 of the preceding calendar year, or a lesser number as may be determined by the Board of Directors of the Company. This Share Reserve number is subject to adjustment in the event of a stock split, reverse stock split, recapitalization or other relevant change in our capitalization. Employee Stock Purchase Plan On August 5, 2020, the Board of Directors adopted, and the OSH LLC’s and OSH MH LLC’s majority equityholders approved, the 2020 Employee Stock Purchase Plan (the “ESPP”) for the issuance of up to a total of 2,386,875 shares of common stock. In addition, the number of shares available for issuance under the ESPP will be increased annually on January 1 of each calendar year beginning in 2021 and ending in and including 2030, by an amount equal to the lesser of (A) 1% of the shares outstanding on the final day of the immediately preceding calendar year and (B) such smaller number of shares as is determined by our Board of Directors, subject to an increase each January. In no event will more than 30,000,000 shares of our common stock will be available for issuance under the ESPP. Each offering period will be approximately six months in duration commencing on January and July 1 of each year and terminating on June 30 or December 31. The ESPP allows participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation. The purchase price of the shares will be 85% of the lower of the fair market value of our common stock on the grant date or purchase date. Emerging Growth Company Status We are an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (“JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period for complying with new or revised accounting standards. Thus, an emerging growth company can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this extended transition period and, as a result, we will not adopt new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies until required by private company accounting standards.
OAK Street Health LLC and Affiliates [Member]
Subsequent Events	NOTE 22. SUBSEQUENT EVENTS Management of the Company has evaluated subsequent events through September 1 6 Initial Public Offering Conversion of Existing Equity While the Company’s Investor Units had no conversion rights related to any of the Investor Unit classes, in response to a reorganization plan to convert the Company into a corporate form, such as the Organizational Transactions discussed in this Note 22 in connection with OSH Inc.’s IPO (per Company’s Amended and Restated Operating Agreement), Investor Unit holders are eligible to receive capital stock of the successor corporation in number of and with terms relatively consistent to their Investor Units, as ultimately determined by the Company’s Board of Directors. In March 2018, the Company’s Board of Directors approved the Amended and Restated Equity Incentive Plan (the “Incentive Plan”). The Incentive Plan states that in the occurrence of an IPO, the Board may, in its discretion, (i) cause the exchange of Incentive Units for units or shares of common stock or other equity securities and apply the vesting provisions applicable to the Incentive Units to such shares of common stock or other equity securities; (ii) adjust the number of Incentive Units issued under the Incentive Plan or under any particular award; (iii) adjust the hurdle value applicable to any Incentive Units; and/or (iv) cancel all or any portion of the Incentive Units in exchange for payment to the Participant in cash or capital stock (or other equity interests) or any combination thereof, of the fair market value of the Incentive Units; in each case, determined by the Board in a manner generally consistent with the treatment of other Units, taking into consideration the relative rights of all Units, including the hurdle value applicable to Incentive Units. Prior to the closing of the IPO, we, and the other direct and indirect equityholders of the Company completed a series of transactions in accordance with the master structuring agreement dated as of August 10, 2020, by and among OSH Inc. and the other signatories party thereto (the “Master Structuring Agreement”) that resulted in OSH Inc. becoming the ultimate parent company of the Company and the current equityholders immediately prior to the close of the IPO exchanged their interests ( Founders Units, I • General Atlantic LLC and Newlight Partners LP (the “Lead Sponsors”) contributed their respective interests in the Company to OSH Inc. in exchange for 126,278,767 shares of common stock in OSH Inc . • OSH MH LLC, the entity through which our employees owned Founders’ Units and r Founders’ Units and profits interests in OSH MH LLC. • The Company merged pursuant to the merger agreement dated August 10, 2020 by and among the Company, OSH Inc., and the other signatory thereto (the “Company Merger”) with and into a newly formed subsidiary of OSH, Inc. with the Company surviving as a wholly owned subsidiary of OSH Inc. Pursuant to the Company Merger, the investors in the Company received a total of 58,467,139 shares of common stock in OSH Inc. in exchange for their Units in the Company. As a result of the abovementioned conversion of existing equity based on the provisions of the Company’s Amended and Restated Operating Agreement, the Company reclassified its existing redeemable preferred units and members’ capital to common stock on the OSH Inc.’s balance sheet. See Note 21, Proforma Information regarding tax impacts related to converting from a LLC to a C corporation. Oak Street Health, LLC is the OSH Inc. predecessor for financial reporting purposes. Issuance of New Shares On August 10, 2020, OSH Inc. completed its IPO in which it issued and sold 17,968,750, shares of its Payoff of Long-Term Debt On August 11, 2020, OSH Inc. used a portion of the net proceeds from the offering to pay off its $80,000 principal outstanding under the Hercules debt agreement, 9.75% interest loan originally due to mature December 2022 in full at a price of 107%. In connection with the voluntary prepayment of the entire remaining borrowings outstanding, OSH Inc. will recognize expense of $3,204 during the third quarter of 2020 related to the prepayment charge, the end of term charge and the write off of unamortized debt issuance costs. The remainder of the net proceeds will be used for general corporate purposes. 2020 Omnibus Incentive Plan On August 5, 2020, OSH Inc.’s Board of Directors adopted the 2020 Omnibus Incentive Plan (the “2020 Plan,”) which was subsequently approved by the majority equityholders of OSH MH LLC and the Company. The 2020 Plan became effective on August 5, 2020. Under the 2020 Plan, pursuant to which employees, consultants and directors of OSH Inc. and its affiliates perform services for them, including their executive officers, will be eligible to receive awards. The 2020 Plan provides for the grant of stock options, stock appreciation rights, restricted shares, performance awards, other share-based awards (including restricted stock units) and other cash-based awards. An aggregate of 26,250,709 shares of common stock is initially available for issuance under the 2020 Plan. The number of shares initially available for issuance will be increased on January 1 of each calendar year, for 10 years, by an amount equal to 5% of the total number of shares outstanding on December 31 of the preceding calendar year, or a lesser number as may be determined by the Board. This number is subject to adjustment in the event of a stock split, reverse stock split, recapitalization or other relevant change in our capitalization. Employee Stock Purchase Plan On August 5, 2020, OSH Inc.’s Board of Directors adopted, and the majority equityholders of OSH MH LLC and the Company approved, the 2020 Employee Stock Purchase Plan (the “ESPP”) for the issuance of up to a total of 2,386,875 shares of common stock. In addition, the number of shares available for issuance under the ESPP will be increased annually on January 1 of each calendar year beginning in 2021 and ending in and including 2030, by an amount equal to the lesser of (A) 1% of the shares outstanding on the final day of the immediately preceding calendar year and (B) such smaller number of shares as is determined by our Board of Directors, subject to an increase each January. In no event will more than 30,000,000 shares of our common stock will be available for issuance under the ESPP. Each offering period will be approximately six months in duration commencing on January and July 1 of each year and terminating on June 30 or December 31. The ESPP allows participants to purchase common stock through payroll deductions of up to 15% of their eligible compensation. The purchase price of the shares will be 85% of the lower of the fair market value of OSH Inc.’s common stock on the grant date or purchase date.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies - (Policies)	6 Months Ended
	Jun. 30, 2020
Significant Accounting Policies [Line Items]
Basis of Accounting	Basis of Accounting The balance sheet is presented in accordance with accounting principles generally accepted in the United States of America. Separate statements of operations, comprehensive income, changes in stockholder’s equity and cash flows have not been presented because there have been no activities in this entity as of June 30, 2020.
OAK Street Health L L C And Affiliates [Member]
Significant Accounting Policies [Line Items]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation Oak Street Health, LLC (“Oak Street Health” or “OSH”) and Affiliates, collectively referred to as “we” or “us” or “our” or the “Company”, operates primary care centers serving Medicare beneficiaries. The Company, through its centers and management services organization, combines an innovative care model with superior patient experience. The Company invests resources into primary care to prevent unnecessary acute events and manage chronic illnesses. The Company engages Medicare eligible patients through the use of an innovative community outreach approach. Once patients are engaged, the Company integrates population health analytics, social support services and primary care into the care model to drive improved outcomes. The Company contracts with health plans to generate medical costs savings and realize a return on its investment in primary care. As of June 30, 2020, the Company operated 54 centers. Oak Street Health is organized as a limited liability company (“LLC”). As such, no member, agent or employee of the Company shall be personally liable for debts, obligations or liabilities of the Company, whether arising in contract, tort, or otherwise or for the acts or omissions of any other member, director, manager, agent or employee of the Company, unless the individual has agreed otherwise under the provisions of the Company’s operating agreement or signed a specific personal guarantee. The duration of the Company is perpetual. Oak Street Health, MSO LLC (“MSO”), a wholly owned subsidiary of Oak Street Health LLC, was formed in 2013 to provide a wide range of management services to the Physician Groups (as defined below). Activities include but are not limited to operational support of the centers, marketing, information technology infrastructure and the sourcing and managing of health plan contracts. Oak Street Health Physicians Group PC, OSH-IN OSH-MI OSH-OH OSH-PA OSH-RI In addition, Oak Street Health is the majority interest owner in three joint ventures: OSH-PCJ OSH-RI, OSH-ESC OSH-ESC The accompanying unaudited interim consolidated financial statements and accompanying notes have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q S-X. six-months COVID-19, The consolidated financial statements of Oak Street Health include the financial statements of all wholly owned subsidiaries and majority-owned or controlled companies. For those consolidated subsidiaries where our ownership is less than 100%, the portion of the net income or loss allocable to the non-controlling non-controlling
Initial Public Offering	Initial Public Offering On August 5, 2020, Oak Street Health, Inc.’s (OSH Inc.’s) Registration Statement on Form S-1 to register 17,968,750 shares of common stock , par value $0.001 per share, was declared effective by the Securities & Exchange Commission. OSH Inc.’s common stock began trading on August 6, 2020 on the New York Stock Exchange (“NYSE”) under the ticker symbol “OSH.” As a result, our consolidated financial statements as of June 30, 2020 do not reflect the impact of the IPO. On August 10, 2020, OSH Inc. completed its IPO in which it issued and shares of its common stock at an offering price per share. The share amount includes the exercise in full of the underwriters’ options to additional shares of common stock. OSH Inc. received net proceeds after deducting underwriting discounts and commissions and estimated deferred offering costs Deferred, direct offering costs are capitalized and consist of fees and expenses incurred in connection with the sale of our common stock in an IPO, including the legal, accounting, printing and other IPO-related equity plans that resulted in conjunction with the IPO in Note 22, Subsequent Events.
Emerging Growth Company Status
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. The areas where significant estimates are used in the accompanying financial statements include the liability for unpaid claims, unit-based compensation, the valuation and related impairment recognition of long-lived assets, including intangibles and goodwill, and the valuation of embedded derivatives and redeemable investor units. Actual results could differ from those estimates. In accordance with its policy, the Company reviews its estimated liability for unpaid claims on an ongoing basis. During the second quarter of 2020, this review indicated that actual medical claims expense was higher than prior period estimates due to a change in our historical payer claim receipt and payment patterns. As a result, as of the period ended June 30, 2020, the Company updated its estimate of its liability of unpaid claims, primarily based on historical experience of medical claims expense. The result of this updated information was additional medical claims expense for the three-months ended June 30, 2020 of approximately $4,599, or $(8.55) per unit (basic and diluted) related to the first quarter of 2020 and $11,344 related to the year ended December 31, 2019, or $(21.10) per unit (basic and diluted). Additionally, for the six-months ended June 30, it resulted in incremental medical claims expense of approximately $11,344 related to the year ended December 31, 2019, or $(19.60) per unit (basic and diluted).
Business Combination	Business Combination On April 2, 2019, the Company entered into an agreement to purchase a primary care center, which constitutes a business, located in Flint, Michigan for cash consideration of $166, which was accounted for under the acquisition method of accounting pursuant to ASC 805. The acquisition is not material to the consolidated financial statements.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In July 2018, the FASB issued ASU 2018-09, Codification Improvements 2018-09”), 2018-09 470-50, Debt Modifications and Extinguishments 718-40, Compensation-Stock Compensation-Income Taxes 2018-09, In August 2018, the FASB issued ASC 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure for Fair Value Measurement 2018-13”), 2018-13
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU 2016-02, Leases 2016-02”), right-of-use 2016-02 2020-05 2016-02 2016-02 2016-02, In July 2017, the FASB issued ASU 2017-11, Earnings Per Unit Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception 2017-11”). 2017-11 2017-11 2017-11 In October 2018, the FASB issued ASU 2018-17, Consolidation – Targeted Improvements to Related Party Guidance for Variable Interest Entities (Topic 810) 2018-17”). 2018-17 2018-17 2018-17 2018-17 In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting 2018-07”) Revenue from Contracts with Customers In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments 2016-13”). 2016-13 off-balance 2016-13 In January 2020, the FASB issued ASU 2020-01, Investments—Equity Securities (Topic 321), Investments—Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815)—Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 (“ASU 2020-01”). 2020-01 2020-01 We do not expect that any other recently issued accounting guidance will have a significant effect on our consolidated financial statements.

Revenue Recognition (Tables)

Revenue Recognition (Tables) - OAK Street Health LLC and Affiliates [Member]	6 Months Ended
	Jun. 30, 2020
Fee-For-Service [Member]
Revenue Recognition [Line Items]
Summary of Sources of Revenue in Percentage Terms	The fee-for-service revenue by payor source for each period presented were as follows: Three-Months Ended June 30, 2020 2019 Medicare 54 % 46 % Humana 6 % 14 % Other 40 % 40 % Six-Months Ended June 30, 2020 2019 Medicare 49 % 46 % Humana 8 % 14 % Other 43 % 40 %
Capitated Revenue [Member]
Revenue Recognition [Line Items]
Summary of Sources of Revenue in Percentage Terms	The Company had agreements in place with the payors listed below and payor sources of capitated revenue for each period presented were as follows: Three-Months Ended June 30, 2020 2019 Humana 47 % 62 % Wellcare 11 % 9 % Cigna-HealthSpring 11 % 9 % Other 31 % 20 % Six-Months Ended June 30, 2020 2019 Humana 48 % 63 % Wellcare 11 % 9 % Cigna-HealthSpring 11 % 9 % Other 30 % 19 %
Other Patient Service Revenue [Member]
Revenue Recognition [Line Items]
Summary of Composition of Revenues	The composition of other patient service revenue for each period was as follows: Three-Months Ended June 30, 2020 2019 Care coordination and care management services $ 5,217 $ 1,873 Fee-for-service 1,168 1,561 Total other patient services revenue $ 6,385 $ 3,434 Six-Months Ended June 30, 2020 2019 Care coordination and care management services $ 9,276 $ 2,456 Fee-for-service 2,304 3,026 Total other patient services revenue $ 11,580 $ 5,482

Property And Equipment (Tables)

Property And Equipment (Tables)	6 Months Ended
	Jun. 30, 2020
OAK Street Health L L C And Affiliates [Member]
Property, Plant and Equipment [Line Items]
Summary of Property Plant and Equipment	Property and equipment consisted of the following as of June 30, 2020 and December 31, 2019: June 30, December 31, Leasehold improvements $ 57,686 $ 56,608 Furniture and fixtures 4,528 3,888 Computer equipment 12,916 9,785 Internal use software 3,088 1,679 Office equipment 9,308 8,934 Construction in process 4,648 3,212 Total property and equipment, at cost 92,174 84,106 Less accumulated depreciation (21,695 ) (16,710 ) Property and equipment, net $ 70,479 $ 67,396

Other Current And Long-Term L_2

Other Current And Long-Term Liabilities (Tables) - OAK Street Health L L C And Affiliates [Member]	6 Months Ended
	Jun. 30, 2020
Other Liabilities [Line Items]
Summary of Accrued Liabilities	Accrued compensation and benefits consisted of the following as of: June 30, 2020 December 31, Accrued paid time off $ 4,427 $ 2,319 Accrued bonus and commission 9,197 16,814 Accrued payroll and taxes 6,558 7,052 Other 2,437 2,425 Total $ 22,619 $ 28,610
Summary of Other Current Liabilities	Other current liabilities consisted of the following as of: June 30, 2020 December 31, Humana license fee $ 3,339 $ 2,753 Lease incentive obligation, current 550 550 Contract liabilities, current 3,107 3,785 Accrual for goods or services received, not invoiced 3,067 2,876 CARES Act stimulus payments 5,434 — Other current liabilities 1,581 1,037 Total $ 17,078 $ 11,001
Summary of Other Noncurrent Liabilities	Other long-term liabilities consisted of the following as of: June 30, 2020 December 31, Contract liabilities, net of current $ 6,371 $ 5,039 Lease incentive obligation, net of current 5,330 5,605 Bifurcated derivative 449 152 CARES Act deferred payroll taxes 1,800 — Other long-term liabilities 20 20 Total $ 13,970 $ 10,816

Liability For Unpaid Claims (Ta

Liability For Unpaid Claims (Tables)	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Summary of Liability for Unpaid Claims and Claims Adjustment Expense	The Company’s liabilities for unpaid claims were June 30, 2020 December 31, Balance, beginning of period $ 170,629 $ 68,174 Incurred health care costs (third-party medical claims expense and administrative health plan fees): Current period 274,687 383,169 Prior period 11,344 268 Total claims incurred 286,031 383,437 Third-party medical claims and administrative health plan fees paid: Current period (160,973 ) (226,618 ) Prior period (59,643 ) (56,220 ) Total claims paid (220,616 ) (282,838 ) Adjustment to other claims-related liabilities (188 ) 1,856 Balance, end of period $ 235,856 $ 170,629

Long- Term Debt (Tables)

Long- Term Debt (Tables) - OAK Street Health LLC and Affiliates [Member]	6 Months Ended
	Jun. 30, 2020
Summary of Long-term Debt Instruments	Long-term debt balances as of the June 30, 2020 and December 31, 2019 wer June 30, 2020 December 31, 2019 Note payable to Hercules Capital, Inc., originally dated August 7, 2017 and amended April 26, 2019 and January 13, 2020. The note bears a floating interest rate of the greater of 9.75% or the sum of the Prime Rate plus 5.00%. $ 80,000 $ 80,000 Plus: Unamortized discount and debt issuance costs 2,126 1,347 Less: Current maturities — (18,507 ) Total long-term debt $ 82,126 $ 62,840
Summary of Maturities of Long-term Debt	Scheduled maturity requirements of long-term debt, excluding the unamortized discount, end of term charge, and debt issuance costs as of June 30, 2020 are as follows: June 30, 2020 2020 $ — 2021 15,212 2022 64,788 Total $ 80,000
Summary of Debt Issuance Costs	Debt issuance costs and original issuance discount as of the periods presented below were as follows: June 30, 2020 December 31, 2019 Accretion of end-of-term $ (2,514 ) $ (1,830 ) Original issuance discount 191 191 Additional issuance discount 543 543 Amortization (346 ) (251 ) Unamortized discount and debt issuance costs, net $ (2,126 ) $ (1,347 )

Redeemable Investor Units (Tabl

Redeemable Investor Units (Tables) - OAK Street Health LLC and Affiliates [Member]	6 Months Ended
	Jun. 30, 2020
Temporary Equity [Line Items]
Summary of redeemable investor units	Redeemable Investor Units consist of the following at the issuance price per unit as of: June 30, 2020 Units Issued Issuance Total Investor Units I 382,572 $ 12.00 $ 4,591 Investor Units II 509,796 16.20 8,259 Investor Units III-A 1,872,409 20.25 37,916 Investor Units III-A 6,043,421 26.38 159,425 Investor Units III-B 568,613 26.38 15,000 Investor Units III-C 747,661 58.78 43,948 Investor Units III-D 876,147 58.78 51,500 Investor Units III-E 1,471,623 156.29 230,000 Total 12,472,242 $ 550,639 December 31, 2019 Units Issued Issuance Total Investor Units I 382,572 $ 12.00 $ 4,591 Investor Units II 509,796 16.20 8,259 Investor Units III-A 1,872,409 20.25 37,916 Investor Units III-A 6,043,421 26.38 159,425 Investor Units III-B 568,613 26.38 15,000 Investor Units III-C 747,661 58.78 43,948 Investor Units III-D 876,147 58.78 51,500 Total 11,000,619 $ 320,639
Summary of investor units activity	The following table shows the Company’s activity related to its Investor Units as of and for the periods ending: Investor Investor Investor III-A Investor III-B Investor III-C Investor III-D Investor III-E Total Outstanding, December 31, 2018 382,572 509,796 7,915,830 568,613 747,661 850,629 — 10,975,101 Issued — — — — — 25,518 — 25,518 Outstanding, December 31, 2019 382,572 509,796 7,915,830 568,613 747,661 876,147 — 11,000,619 Issued — — — — — — 1,471,623 1,471,623 Outstanding, June 30, 2020 382,572 509,796 7,915,830 568,613 747,661 876,147 1,471,623 12,472,242
Schedule of dividends preferred stock	The following table shows accumulated dividends on the redeemable Investor Units on a cumulative basis as of the periods ended: June 30, 2020 December 31, 2019 Units Per Total Units Per Total Series Investor Units I 382,572 $ 8.36 $ 3,200 382,572 $ 7.60 $ 2,908 Investor Units II 509,796 9.93 5,063 509,796 8.95 4,563 Investor Units III-A 1,872,409 10.23 19,163 1,872,409 9.09 17,020 Investor Units III-A 6,043,421 7.62 46,037 6,043,421 6.34 38,322 Investor Units III-B 568,613 5.24 2,981 568,613 4.06 2,306 Investor Units III-C 747,661 10.76 8,041 747,661 8.14 6,089 Investor Units III-D 876,147 8.41 7,372 876,147 5.89 5,162 Investor Units III-E 1,471,623 4.29 6,315 — — — Total $ 98,172 $ 76,370

Members' Deficit (Tables)

Members' Deficit (Tables) - OAK Street Health LLC and Affiliates [Member]	6 Months Ended
	Jun. 30, 2020
Limited Liability Company LLC Members Equity [Line Items]
Summary of common units outstanding	The Company’s common units consists of the following Founders’ Units, Incentive Units, and Profits Interests (see Note 14) as of June 30: Founders’ Incentive Profits Total Outstanding, December 31, 2018 606,313 13,755 1,454,148 2,074,216 Granted — — 496,763 496,763 Repurchased/Forfeited — — (40,115 ) (40,115 ) Outstanding, December 31, 2019 606,313 13,755 1,910,796 2,530,864 Granted — — 1,095,067 1,095,067 Repurchased/Forfeited — — (33,320 ) (33,320 ) Tender Offer (107,208 ) (1,142 ) (22,801 ) (131,151 ) Outstanding June 30, 2020 499,105 12,613 2,949,742 3,461,460
Summary of common units tendered	The following units were tendered to the Company: Type of Units Number of Purchase Total Founders’ Units 107,208 $ 156.29 $ 16,756 Incentive Units 1,142 156.29 178 Profits Interest Hurdle Value $265,158 17,622 136.04 2,397 Profits Interest Hurdle Value $346,107 3,684 129.91 479 Profits Interest Hurdle Value $386,277 1,495 126.90 190 Total Common Units 131,151 20,000

Unit-Based Compensation (Tables

Unit-Based Compensation (Tables) - OAK Street Health L L C And Affiliates [Member]	6 Months Ended
	Jun. 30, 2020
Summary of Unit-Based Compensation awards Valuation Assumptions	Accordingly, the Company determined the fair value of each award on the date of grant using both the income and market approaches, including the backsolve method with the following assumptions used for grants issued for the three and six-months Six-Months Ended June 30, 2020 2019 Risk-Free Rate .16 % 1.58 % Volatility 65.0 % 35.00 % Time to Liquidity Event (Years) 2.00 2.19
Summary of Profits Interests Award Activity	The following is a summary of Profits Interests award transactions as well as the Profits Interests outstanding and their corresponding hurdle values as of and for the periods ended June 30, 2020 and December 31, 2019: Profits Interests Weighted-Average Outstanding, December 31, 2018 1,454,148 2.35 Granted 496,763 42.35 Vested 193,375 2.32 Forfeited/Repurchased (40,115 ) 5.74 Outstanding, December 31, 2019 1,910,796 12.68 Granted 1,095,067 53.51 Vested 188,381 5.09 Forfeited/Repurchased (56,121 ) 10.01 Outstanding, June 30, 2020 2,949,742 11.32 Vested outstanding, June 30, 2020 550,698 Vested outstanding, December 31, 2019 389,531 As of June 30, 2020 As of December 31, 2019 Units Outstanding Hurdle Value Units Hurdle 93,455 $ 265,158 111,076 $ 234,834 151,370 346,107 160,492 306,706 43,780 386,277 45,275 342,451 253,874 685,350 265,374 608,955 510,450 782,361 462,292 645,000 458,090 922,500 521,225 697,700 343,656 1,582,500 345,062 1,310,000 380,250 2,200,000 — — 714,817 2,210,000 — — Total 2,949,742 Total 1,910,796

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Summary of VIE Assets and Liabilities and Performance for the Physician Groups	The table below illustrates the VIE assets and liabilities and performance for the Physician Groups as of and for the periods ended: June 30, 2020 December 31, 2019 Total assets $ 363,307 $ 252,629 Total liabilities 301,621 230,527 Three-Months Ended June 30, 2020 2019 Total revenues $ 210,314 $ 125,215 Operating expenses: Medical claims expense 154,656 83,577 Cost of care, excluding depreciation and amortization 14,187 9,229 Total operating expenses $ 168,843 $ 92,806 Six-Months June 30, 2020 2019 Total revenues $ 408,778 $ 242,591 Operating expenses: Medical claims expense 286,032 160,271 Cost of care, excluding depreciation and amortization 29,534 17,180 Total operating expenses $ 315,566 $ 177,451

Net Loss Per Unit (Tables)

Net Loss Per Unit (Tables)	6 Months Ended
	Jun. 30, 2020
OAK Street Health LLC and Affiliates [Member]
Summary of Basic and Diluted Net Loss Per Common Unit	The following table sets forth the computation of basic and diluted net loss per common unit for the three-months ended June 30: June 30, June 30, Net loss attributable to unitholders – basic and diluted: Net loss attributable to the Company $ (26,765 ) $ (20,161 ) Less: Undeclared and deemed dividends on Investor Units (12,230 ) (7,188 ) Net loss attributable to common unitholders (38,995 ) (27,349 ) Weighted average common units outstanding 537,654 620,068 Net loss attributable to common unitholders – basic and diluted $ (72.53 ) $ (44.11 ) Potentially dilutive securities excluded from the computation of diluted net loss per unit because including them would have been anti-dilutive Options to purchase Incentive Units 2,000 2,000 Profits Interests 2,949,742 1,675,091 Total 2,951,742 1,677,091 The following table sets forth the computation of basic and diluted net loss per common unit for the six-months June 30, June 30, Net loss attributable to unitholders – basic and diluted: Net loss attributable to the Company $ (41,765 ) $ (30,156 ) Less: Undeclared and deemed dividends on Investor Units (21,802 ) (14,302 ) Net loss attributable to common unitholders (63,567 ) (44,458 ) Weighted average common units outstanding 578,861 620,068 Net loss attributable to common unitholders – basic and diluted $ (109.81 ) $ (71.70 ) Potentially dilutive securities excluded from the computation of diluted net loss per unit because including them would have been Options to purchase Incentive Units 2,000 2,000 Profits Interests 2,949,742 1,675,091 Total 2,951,742 1,675,091

Organization - Additional Infor

Organization - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2020
Organisation incorporated date	Oct. 22, 2019

Nature of Business - Additional

Nature of Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Aug. 10, 2020	Apr. 02, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Aug. 05, 2020
Nature of Business [Line Items]
Shares of common stock was declared effective			1,000			1,000
Common stock, par value			$ 0.001			$ 0.001		$ 0.001
OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Stock issued during period shares						1,471,623		25,518
Deferred offering costs	$ 3,000
Payments to acquire businesses, gross							$ 166
Deferred payroll taxes			$ 1,800			$ 1,800
Contract liabilities, current			$ 3,107			$ 3,107		$ 3,785
Mediclaim expenses								$ 11,344
Net loss per unit – basic and diluted			$ (72.53)	$ (44.11)		$ (109.81)	$ (71.70)	$ (21.10)
Common stock, par value			$ 0.01			$ 0.01		$ 0.01
OAK Street Health LLC and Affiliates [Member] | Grant [Member]
Nature of Business [Line Items]
Grants received						$ 4,698
Grant received included in other current liabilities			$ 3,914			$ 3,914
OAK Street Health LLC and Affiliates [Member] | Medicare Accelerated Advanced Payment Scheme [Member] | CARES Act [Member]
Nature of Business [Line Items]
Percentage of interest free loans received						100.00%
Period after mediclaim issue when advance payments will begin						120 days
Period after mediclaim issue when advance payments are due						210 days
Proceeds from short term debt			1,520
Contract liabilities, current			1,520			$ 1,520
OAK Street Health LLC and Affiliates [Member] | Revenue Benchmark [Member]
Nature of Business [Line Items]
Concentration risk percentage						97.00%
Medical Claims Expenses [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Mediclaim expenses			155,460	$ 84,345		$ 287,745	$ 161,619	$ 11,344
Medical Claims Expenses [Member] | OAK Street Health LLC and Affiliates [Member] | Change in Accounting Method Accounted for as Change in Estimate [Member]
Nature of Business [Line Items]
Mediclaim expenses			$ 4,599					$ 11,344
Net loss per unit – basic and diluted			$ (8.55)					$ (19.60)
Cost of Care [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Mediclaim expenses			$ 39,526	$ 31,429		83,294	$ 59,073
Cost of Care [Member] | OAK Street Health LLC and Affiliates [Member] | Grant [Member] | CARES Act [Member]
Nature of Business [Line Items]
Grants received recognized						784
Primary Care Center [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Payments to acquire businesses, gross		$ 166
Subsequent Event [Member]
Nature of Business [Line Items]
Shares of common stock was declared effective	500,000,000
Proceeds from issuance of initial public offering	$ 351,703
Payments for underwriting expense	22,641
Deferred offering costs	$ 3,000
Common stock, par value	$ 0.001
Subsequent Event [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Stock issued during period shares	17,968,750
Proceeds from issuance of initial public offering	$ 351,703
Payments for underwriting expense	22,641
Deferred offering costs	$ 3,000
IPO [Member] | Subsequent Event [Member]
Nature of Business [Line Items]
Shares of common stock was declared effective									17,968,750
Stock issued during period shares	17,968,750
Shares offering, price per share	$ 21
Common stock, par value									$ 0.001
IPO [Member] | Subsequent Event [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Shares of common stock was declared effective									17,968,750
Stock issued during period shares	17,968,750
Shares offering, price per share	$ 21
Common stock, par value									$ 0.001
Over-Allotment Option [Member] | Subsequent Event [Member]
Nature of Business [Line Items]
Stock issued during period shares	2,343,750
Over-Allotment Option [Member] | Subsequent Event [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Stock issued during period shares	2,343,750
Corporate Joint Venture [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Contributions made to joint ventures						$ 0
Oak Street Health MSO LLC [Member] | Corporate Joint Venture [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Contributions made to joint ventures					$ 2,754
Ownership percentage in joint ventures					51.00%
Evangelical Services Corporation [Member] | Corporate Joint Venture [Member] | OAK Street Health LLC and Affiliates [Member]
Nature of Business [Line Items]
Contributions made to joint ventures					$ 2,646
Ownership percentage in joint ventures					49.00%

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	1,000
Common stock, shares, issued	0
Common stock, shares, outstanding	0

Revenue Recognition - Summary o

Revenue Recognition - Summary of Sources of Capitated Revenue (Detail) - Capitated Revenue [Member] - OAK Street Health L L C And Affiliates [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Humana [Member]
Disclosure Of Sources Of Revenue In Percentage Terms [Line Items]
Concentration risk percentage	47.00%	62.00%	48.00%	63.00%
Wellcare [Member]
Disclosure Of Sources Of Revenue In Percentage Terms [Line Items]
Concentration risk percentage	11.00%	9.00%	11.00%	9.00%
Cigna-HealthSpring [Member]
Disclosure Of Sources Of Revenue In Percentage Terms [Line Items]
Concentration risk percentage	11.00%	9.00%	11.00%	9.00%
Other [Member]
Disclosure Of Sources Of Revenue In Percentage Terms [Line Items]
Concentration risk percentage	31.00%	20.00%	30.00%	19.00%

Revenue Recognition - Summary_2

Revenue Recognition - Summary of Composition Of Revenues (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Performance obligations revenue recognised	$ 214,382	$ 126,488	$ 416,167	$ 243,865
Other Patient Service Revenue [Member]
Disaggregation of Revenue [Line Items]
Performance obligations revenue recognised	6,385	3,434	11,580	5,482
Care Coordination And Care Management Services [Member] | Other Patient Service Revenue [Member]
Disaggregation of Revenue [Line Items]
Performance obligations revenue recognised	5,217	1,873	9,276	2,456
Fee-For-Service [Member] | Other Patient Service Revenue [Member]
Disaggregation of Revenue [Line Items]
Performance obligations revenue recognised	$ 1,168	$ 1,561	$ 2,304	$ 3,026

Revenue Recognition - Summary_3

Revenue Recognition - Summary of Sources of Fee for Service Revenue (Detail) - Fee-For-Service [Member] - Other Patient Service Revenue [Member] - OAK Street Health L L C And Affiliates [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Medicare [Member]
Disclosure Of Sources Of Revenue In Percentage Terms [Line Items]
Concentration risk percentage	54.00%	46.00%	49.00%	46.00%
Humana [Member]
Disclosure Of Sources Of Revenue In Percentage Terms [Line Items]
Concentration risk percentage	6.00%	14.00%	8.00%	14.00%
Other [Member]
Disclosure Of Sources Of Revenue In Percentage Terms [Line Items]
Concentration risk percentage	40.00%	40.00%	43.00%	40.00%

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue From Contract With Customer Line Items [Line Items]
Cost of care	$ 316	$ 905	$ 1,780	$ 1,755
Cost of providing patient care in relation to revenue waived					$ 11,344
Cost Of Care [Member]
Revenue From Contract With Customer Line Items [Line Items]
Cost of providing patient care in relation to revenue waived	39,526	31,429	83,294	59,073
Financial Support, Waived Fees [Member] | Cost Of Care [Member]
Revenue From Contract With Customer Line Items [Line Items]
Cost of providing patient care in relation to revenue waived	530	1,521	2,991	2,948
Humana [Member] | Cost Of Care [Member]
Revenue From Contract With Customer Line Items [Line Items]
Cost of providing patient care in relation to revenue waived	$ 1,235	$ 869	$ 2,405	$ 1,559
Medicare Part D [Member] | Medical Claims Expenditure [Member]
Revenue From Contract With Customer Line Items [Line Items]
Concentration risk percentage	3.00%	5.00%	3.00%	5.00%
Capitated Revenue [Member] | Humana [Member]
Revenue From Contract With Customer Line Items [Line Items]
Concentration risk percentage	47.00%	62.00%	48.00%	63.00%
Capitated Revenue [Member] | Others [Member]
Revenue From Contract With Customer Line Items [Line Items]
Concentration risk percentage	31.00%	20.00%	30.00%	19.00%
Capitated Revenue [Member] | Medicare Part D [Member]
Revenue From Contract With Customer Line Items [Line Items]
Concentration risk percentage	2.00%	3.00%	2.00%	3.00%
Other Patient Service Revenue [Member] | Accounts Receivable [Member] | Medicare [Member]
Revenue From Contract With Customer Line Items [Line Items]
Concentration risk percentage			41.00%		47.00%
Other Patient Service Revenue [Member] | Accounts Receivable [Member] | Humana [Member]
Revenue From Contract With Customer Line Items [Line Items]
Concentration risk percentage			7.00%		9.00%
Other Patient Service Revenue [Member] | Accounts Receivable [Member] | Others [Member]
Revenue From Contract With Customer Line Items [Line Items]
Concentration risk percentage			52.00%		44.00%
Accounting Standards Update 2014-09 [Member] | Acuity Adjustment [Member] | Capitated Revenue [Member]
Revenue From Contract With Customer Line Items [Line Items]
Performance obligations revenue recognised	$ 22,615	$ 1,584	$ 46,143	$ 3,133

Fair Value of Financial Measure

Fair Value of Financial Measurement - Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value measurements for the bifurcated derivative	$ 449		$ 449		$ 152
Interest Expense [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Changes in fair value of the bifurcated derivative	200	$ 308	297	$ 489
Other Noncurrent Liabilities [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value measurements for the bifurcated derivative	$ 449		$ 449		$ 152

Property And Equipment - Summar

Property And Equipment - Summary of Property Plant and Equipment (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 92,174	$ 84,106
Less accumulated depreciation	(21,695)	(16,710)
Property, plant and equipment, net	70,479	67,396
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	57,686	56,608
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,528	3,888
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,916	9,785
Internal Use Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,088	1,679
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,308	8,934
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 4,648	$ 3,212

Property And Equipment - Additi

Property And Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
OAK Street Health L L C And Affiliates [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 2,577	$ 1,760	$ 4,985	$ 3,388

Goodwill And Intangible Assets

Goodwill And Intangible Assets - Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	Oct. 01, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Goodwill and Intangible Assets [Line Items]
Goodwill		$ 9,634		$ 9,634		$ 9,634
Goodwill, impairment loss	$ 0
Net intangible assets		3,159		3,159		$ 3,352
Amortization of intangible assets		$ 97	$ 97	$ 193	$ 193

Internal Use Software - Additio

Internal Use Software - Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Internal Use Software [Line Items]
Internal use of software, capitalized	$ 3,088		$ 3,088		$ 1,679
Internal use of software, accumulated depreciation	469		469		$ 327
Capitalized development costs expensed	$ 78	$ 32	$ 141	$ 62

Other Current And Long -Term Li

Other Current And Long -Term Liabilities - Summary of Accrued Liabilities (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Other Liabilities [Line Items]
Accrued paid time off	$ 4,427	$ 2,319
Accrued bonus and commission	9,197	16,814
Accrued payroll and taxes	6,558	7,052
Other	2,437	2,425
Total	$ 22,619	$ 28,610

Other Current And Long -Term _2

Other Current And Long -Term Liabilities - Summary of Other Current Liabilities (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Other Liabilities [Line Items]
Humana license fee	$ 3,339	$ 2,753
Lease incentive obligation, current	550	550
Contract liabilities, current	3,107	3,785
Accrual for goods or services received, not invoiced	3,067	2,876
CARES Act stimulus payments	5,434	0
Other current liabilities	1,581	1,037
Total	$ 17,078	$ 11,001

Other Current And Long -Term _3

Other Current And Long -Term Liabilities - Summary of Other Noncurrent Liabilities (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Contract liabilities, net of current	$ 6,371	$ 5,039
Lease incentive obligation, net of current	5,330	5,605
Bifurcated derivative	449	152
CARES Act deferred payroll taxes	1,800	0
Other long-term liabilities	20	20
Total	$ 13,970	$ 10,816

Liability For Unpaid Claims - S

Liability For Unpaid Claims - Summary of Liability for Unpaid Claims and Claims Adjustment Expense (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Balance, beginning of period	$ 170,629	$ 68,174
Incurred health care costs (third-party medical claims expense and administrative health plan fees):
Current period	274,687	383,169
Prior period	11,344	268
Total claims incurred	286,031	383,437
Third-party medical claims and administrative health plan fees paid:
Current period	(160,973)	(226,618)
Prior period	(59,643)	(56,220)
Total claims paid	(220,616)	(282,838)
Adjustment to other claims-related liabilities	(188)	1,856
Balance, end of period	$ 235,856	$ 170,629

Liability For Unpaid Claims- Ad

Liability For Unpaid Claims- Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Liability for unpaid claims	$ 235,856	$ 170,629	$ 235,856	$ 170,629	$ 170,629	$ 68,174
Mediclaim expenses					$ 11,344
Earning per share basic and diluted	$ (72.53)	$ (44.11)	$ (109.81)	$ (71.70)	$ (21.10)
Medical Claims Expenses [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Mediclaim expenses	$ 155,460	$ 84,345	$ 287,745	$ 161,619	$ 11,344
Medical Claims Expenses [Member] | Restatement Adjustment [Member] | Twelve Months Ending Thirty First December Two Thousand And Nineteen [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Mediclaim expenses					$ 11,344
Earning per share basic and diluted					$ (19.60)
Medical Claims Expenses [Member] | Restatement Adjustment [Member] | Three Months Ending Thirty June Two Thousand And Twenty [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Mediclaim expenses	$ 4,599
Earning per share basic and diluted	$ (8.55)
Provider Excess Insurance Scheme [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Insurance premium expenditure incurred	$ 869	448	1,712	958
Insurance premium expenditure reimbursed	$ 446	$ 0	752	$ 0
Providers excess insurance deductible per member			250
Provider Excess Insurance Scheme [Member] | Maximum [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Providers excess insurance deductible per member			$ 5,000

Long- Term Debt - Summary of Lo

Long- Term Debt - Summary of Long-term Debt Instruments (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Note payable to Hercules Capital, Inc., originally dated August 7, 2017 and amended April 26, 2019 and January 13, 2020. The note bears a floating interest rate of the greater of 9.75% or the sum of the Prime Rate plus 5.00%.	$ 80,000	$ 80,000
Plus: Unamortized discount and debt issuance costs	2,126	1,347
Less: Current maturities		(18,507)
Total long-term debt	$ 82,126	$ 62,840

Long- Term Debt - Summary of _2

Long- Term Debt - Summary of Long-term Debt Instruments (Parenthetical) (Detail) - Notes Payable, Other Payables [Member] - Hercules Capital Inc [Member] - OAK Street Health LLC and Affiliates [Member]	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Aug. 07, 2017
Debt Instrument [Line Items]
Long term debt variable interest rate percentage	9.75%	9.75%	9.75%
Long term debt description of variable interest rate spread	Prime Rate plus 5.00%.
Debt instrument issue date	Aug. 7, 2017

Long- Term Debt - Additional In

Long- Term Debt - Additional Information (Detail) - USD ($) $ in Thousands

Jun. 28, 2018

Jun. 30, 2020

Jun. 30, 2019

Jun. 30, 2020

Dec. 31, 2017

Jun. 30, 2020

Jun. 30, 2019

Dec. 31, 2017

Dec. 31, 2019

Dec. 31, 2017

Jun. 30, 2020

Feb. 01, 2020

Jul. 01, 2019

Apr. 26, 2019

Apr. 01, 2019

Aug. 07, 2017

OAK Street Health LLC and Affiliates [Member]

Debt Instrument [Line Items]

Proceeds from long term debt

$ 29,457

Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member]

Debt Instrument [Line Items]

Derivative liability

$ 449

$ 449

$ 449

$ 152

$ 449

Debt instrument accrual of end of term charge

4,760

$ 4,760

4,760

$ 4,760

$ 4,760

Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Interest Expense [Member]

Debt Instrument [Line Items]

Gain loss due to changes in fair value of derivative liability

$ 200

$ 308

$ 297

$ (489)

Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Interest [Member]

Debt Instrument [Line Items]

Debt instrument frequency of periodic payment

13 months

Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Principal [Member]

Debt Instrument [Line Items]

Debt instrument frequency of periodic payment

36 month

Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Principal And End Of Term Charge [Member]

Debt Instrument [Line Items]

Long term debt instrument maturity

Sep. 1, 2021

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 20,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Long term debt instrument maturity

Jun. 1, 2022

Debt instrument end of term charge in percentage terms

5.95%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Debt Instrument Amendment Agreement Two [Member]

Debt Instrument [Line Items]

Long term debt variable interest rate percentage

9.75%

Long term debt description of variable interest rate spread

prime rate plus 5.00%

Debt instrument variable interest rate spread

5.00%

Long term debt instrument maturity

Dec. 1, 2022

Debt instrument maturity start date

Oct. 1, 2021

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Tranche One [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 30,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Tranche Two [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 30,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Tranche Three [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 20,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Tranche Four [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

10,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Interest [Member] | Debt Instrument Amendment Agreement Two [Member]

Debt Instrument [Line Items]

Debt instrument maturity start date

Jul. 1, 2020

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Prepayment On Or Before Thirteenth June Two Thousand And Twenty [Member] | Debt Instrument Amendment Agreement Two [Member]

Debt Instrument [Line Items]

Long term debt prepayment penalty percentage

2.00%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | Prepayment After Thirteenth June Two Thousand And Twenty But Before Thirty First December Two Thousand And Twenty [Member] | Debt Instrument Amendment Agreement Two [Member]

Debt Instrument [Line Items]

Long term debt prepayment penalty percentage

1.00%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 20,000

Long term debt variable interest rate percentage

9.75%

9.75%

9.75%

9.75%

9.75%

9.75%

Long term debt description of variable interest rate spread

Prime Rate plus 5.00%.

Debt instrument variable interest rate spread

4.75%

4.75%

Proceeds from long term debt

$ 10,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Base Rate [Member]

Debt Instrument [Line Items]

Long term debt variable interest rate percentage

9.75%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Long term debt instrument maturity

Jun. 1, 2022

Debt instrument end of term charge in percentage terms

5.95%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Debt Instrument Amendment Agreement Two [Member]

Debt Instrument [Line Items]

Long term debt description of variable interest rate spread

the Prime Rate minus 4.75%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Tranche One [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 30,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Tranche Two [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 30,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Tranche Three [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

20,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Tranche Four [Member] | Debt Instrument Amendment Agreement One [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 10,000

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Within Twelve Months From The Closing Date [Member]

Debt Instrument [Line Items]

Long term debt prepayment penalty percentage

3.00%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | After Twelve Months And Within Twenty Four Months From The Closing Date [Member]

Debt Instrument [Line Items]

Long term debt prepayment penalty percentage

2.00%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | After Twenty Four Months From The Closing Date [Member]

Debt Instrument [Line Items]

Long term debt prepayment penalty percentage

1.00%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Maximum [Member]

Debt Instrument [Line Items]

Long term debt prepayment penalty percentage

3.00%

Notes Payable, Other Payables [Member] | Hercules Capital Inc [Member] | OAK Street Health LLC and Affiliates [Member] | Minimum [Member]

Debt Instrument [Line Items]

Long term debt prepayment penalty percentage

1.00%

Long- Term Debt - Summary of Ma

Long- Term Debt - Summary of Maturities of Long-term Debt (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule of Maturities of Long term Debt [Line Items]
2021	$ 15,212
2022	64,788
Total	$ 80,000	$ 80,000

Long- Term Debt - Summary of D

Long- Term Debt - Summary of Debt Issuance Costs (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule Of Debt Issuance Costs [Line Items]
Accretion of end-of-term charge	$ (2,514)	$ (1,830)
Original issuance discount	191	191
Additional issuance discount	543	543
Amortization	(346)	(251)
Unamortized discount and debt issuance costs, net	$ (2,126)	$ (1,347)

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member]	6 Months Ended
	Jun. 30, 2020USD ($)
Net deferred tax assets	$ 0
Effective income tax rate	0.00%

Redeemable Investor Units - Sum

Redeemable Investor Units - Summary of Redeemable Investor Units (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Units Issued and Outstanding	12,472,242	11,000,619	10,975,101
Total Value	$ 550,639	$ 320,639
Investor Units I [Member]
Temporary Equity [Line Items]
Units Issued and Outstanding	382,572	382,572	382,572
Issuance Price per Unit	$ 12	$ 12
Total Value	$ 4,591	$ 4,591
Investor Units II [Member]
Temporary Equity [Line Items]
Units Issued and Outstanding	509,796	509,796	509,796
Issuance Price per Unit	$ 16.20	$ 16.20
Total Value	$ 8,259	$ 8,259
Investor Units III-A – Issued prior to December 1, 2015 [Member]
Temporary Equity [Line Items]
Units Issued and Outstanding	1,872,409	1,872,409
Issuance Price per Unit	$ 20.25	$ 20.25
Total Value	$ 37,916	$ 37,916
Investor Units III-A – Issued after December 1,2015 [Member]
Temporary Equity [Line Items]
Units Issued and Outstanding	6,043,421	6,043,421
Issuance Price per Unit	$ 26.38	$ 26.38
Total Value	$ 159,425	$ 159,425
Investor Units III-B [Member]
Temporary Equity [Line Items]
Units Issued and Outstanding	568,613	568,613	568,613
Issuance Price per Unit	$ 26.38	$ 26.38
Total Value	$ 15,000	$ 15,000
Investor Units III-C [Member]
Temporary Equity [Line Items]
Units Issued and Outstanding	747,661	747,661	747,661
Issuance Price per Unit	$ 58.78	$ 58.78
Total Value	$ 43,948	$ 43,948
Investor Units III-D [Member]
Temporary Equity [Line Items]
Units Issued and Outstanding	876,147	876,147	850,629
Issuance Price per Unit	$ 58.78	$ 58.78
Total Value	$ 51,500	$ 51,500
Investor Units III-E [Meber]
Temporary Equity [Line Items]
Units Issued and Outstanding	1,471,623
Issuance Price per Unit	$ 156.29
Total Value	$ 230,000

Redeemable Investor Units - S_2

Redeemable Investor Units - Summary of Investor Units Activity (Detail) - OAK Street Health LLC and Affiliates [Member] - shares	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Temporary Equity [Line Items]
Beginning balance	11,000,619	10,975,101
Issued	1,471,623	25,518
Ending Balance	12,472,242	11,000,619
Investor Units I [Member]
Temporary Equity [Line Items]
Beginning balance	382,572	382,572
Issued
Ending Balance	382,572	382,572
Investor Units II [Member]
Temporary Equity [Line Items]
Beginning balance	509,796	509,796
Issued
Ending Balance	509,796	509,796
Investor Units III-A [Member]
Temporary Equity [Line Items]
Beginning balance	7,915,830	7,915,830
Issued
Ending Balance	7,915,830	7,915,830
Investor Units III-B [Member]
Temporary Equity [Line Items]
Beginning balance	568,613	568,613
Issued
Ending Balance	568,613	568,613
Investor Units III-C [Member]
Temporary Equity [Line Items]
Beginning balance	747,661	747,661
Issued
Ending Balance	747,661	747,661
Investor Units III-D [Member]
Temporary Equity [Line Items]
Beginning balance	876,147	850,629
Issued		25,518
Ending Balance	876,147	876,147
Investor Units III-E [Meber]
Temporary Equity [Line Items]
Beginning balance
Issued	1,471,623
Ending Balance	1,471,623

Redeemable Investor Units - S_3

Redeemable Investor Units - Summary of Dividends Preferred Stock (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Units	12,472,242	11,000,619	10,975,101
Total	$ 98,172	$ 76,370
Investor Units I [Member]
Temporary Equity [Line Items]
Units	382,572	382,572	382,572
Per Unit	$ 8.36	$ 7.60
Total	$ 3,200	$ 2,908
Investor Units II [Member]
Temporary Equity [Line Items]
Units	509,796	509,796	509,796
Per Unit	$ 9.93	$ 8.95
Total	$ 5,063	$ 4,563
Investor Units III-A – Issued prior to December 1, 2015 [Member]
Temporary Equity [Line Items]
Units	1,872,409	1,872,409
Per Unit	$ 10.23	$ 9.09
Total	$ 19,163	$ 17,020
Investor Units III-A – Issued after to December 1,2015 [Member]
Temporary Equity [Line Items]
Units	6,043,421	6,043,421
Per Unit	$ 7.62	$ 6.34
Total	$ 46,037	$ 38,322
Investor Units III-B [Member]
Temporary Equity [Line Items]
Units	568,613	568,613	568,613
Per Unit	$ 5.24	$ 4.06
Total	$ 2,981	$ 2,306
Investor Units III-C [Member]
Temporary Equity [Line Items]
Units	747,661	747,661	747,661
Per Unit	$ 10.76	$ 8.14
Total	$ 8,041	$ 6,089
Investor Units III-D [Member]
Temporary Equity [Line Items]
Units	876,147	876,147	850,629
Per Unit	$ 8.41	$ 5.89
Total	$ 7,372	$ 5,162
Investor Units III-E [Member]
Temporary Equity [Line Items]
Units	1,471,623
Per Unit	$ 4.29
Total	$ 6,315

Redeemable Investor Units - Add

Redeemable Investor Units - Additional Information (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Issuance of Series I, II and III Investor Units (In Shares)		1,471,623		25,518
Proceeds From Issuance Of Investor Units	$ (268,707)	$ (401,313)	$ (268,707)	$ (344,878)	$ (358,412)	$ (248,813)	$ (241,810)
Investor Units Dividend Declared		$ 0		$ 0
Redeemable Investor Units [Member]
Temporary Equity [Line Items]
Temporary Equity, Shares Authorized		100,000,000
Issuance of Series I, II and III Investor Units	$ 1,500	$ 224,363	$ 1,500
Limited Liability Company (LLC) Member, Preferred Return Percentage		8.00%
Investor Units III-D [Member]
Temporary Equity [Line Items]
Issuance of Series I, II and III Investor Units (In Shares)				25,518
Shares Issued, Price Per Share		$ 58.78		$ 58.78
Investor Units III-D [Member] | Redeemable Investor Units [Member]
Temporary Equity [Line Items]
Issuance of Series I, II and III Investor Units		$ 1,500
Investor Units III-E [Member]
Temporary Equity [Line Items]
Issuance of Series I, II and III Investor Units (In Shares)		1,471,623
Shares Issued, Price Per Share		$ 156.29
Proceeds From Issuance Of Investor Units		$ 230,000
Payments Of Stock Issuance Costs		$ 5,637

Members' Deficit - Summary of C

Members' Deficit - Summary of Common Units Outstanding (Detail) - shares	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Limited Liability Company LLC Members Equity [Line Items]
Beginning balance	0
Ending balance	0	0
OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Beginning balance	2,530,864	2,074,216
Granted	1,095,067	496,763
Repurchased/Forfeited	(33,320)	(40,115)
Tender Offer	(131,151)
Ending balance	3,461,460	2,530,864
Founders Units [Member] | OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Beginning balance	606,313	606,313
Tender Offer	(107,208)
Ending balance	499,105	606,313
Incentive Units [Member] | OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Beginning balance	13,755	13,755
Tender Offer	(1,142)
Ending balance	12,613	13,755
Profits Interest [Member] | OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Beginning balance	1,910,796	1,454,148
Granted	1,095,067	496,763
Repurchased/Forfeited	(33,320)	(40,115)
Tender Offer	(22,801)
Ending balance	2,949,742	1,910,796

Members' Deficit - Summary of_2

Members' Deficit - Summary of Common Units Outstanding (Parenthetical) (Detail) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Limited Liability Company LLC Members Equity [Line Items]
Common units or stated par value per unit	$ 0.001	$ 0.001
OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Common units or stated par value per unit	0.01	$ 0.01
Founders Units [Member] | OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Common units or stated par value per unit	0.01
Incentive Units [Member] | Minimum [Member] | OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Common units or stated par value per unit	0
Incentive Units [Member] | Maximum [Member] | OAK Street Health LLC and Affiliates [Member]
Limited Liability Company LLC Members Equity [Line Items]
Common units or stated par value per unit	26
Profits Interest [Member]
Limited Liability Company LLC Members Equity [Line Items]
Common units or stated par value per unit	$ 0

Members' Deficit - Summary of_3

Members' Deficit - Summary of Common Units Tendered (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ / shares in Units, $ in Thousands	Apr. 27, 2020	Jun. 30, 2020
Limited Liability Company LLC Members Equity [Line Items]
Number of Units Tendered		131,151
Purchase Price per Unit	$ 156.29
Total Purchase Price	$ 20,000	$ 20,000
Founders Units [Member]
Limited Liability Company LLC Members Equity [Line Items]
Number of Units Tendered		107,208
Purchase Price per Unit		$ 156.29
Total Purchase Price		$ 16,756
Incentive Units [Member]
Limited Liability Company LLC Members Equity [Line Items]
Number of Units Tendered		1,142
Purchase Price per Unit		$ 156.29
Total Purchase Price		$ 178
Profits Interest [Member] | Hurdle Value One [Member]
Limited Liability Company LLC Members Equity [Line Items]
Number of Units Tendered		17,622
Purchase Price per Unit		$ 136.04
Total Purchase Price		$ 2,397
Profits Interest [Member] | Hurdle Value Two [Member]
Limited Liability Company LLC Members Equity [Line Items]
Number of Units Tendered		3,684
Purchase Price per Unit		$ 129.91
Total Purchase Price		$ 479
Profits Interest [Member] | Hurdle Value Three [Member]
Limited Liability Company LLC Members Equity [Line Items]
Number of Units Tendered		1,495
Purchase Price per Unit		$ 126.90
Total Purchase Price		$ 190

Members' Deficit - Summary of_4

Members' Deficit - Summary of Common Units Tendered (Parenthetical) (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Hurdle Value One [Member]
Limited Liability Company LLC Members Equity [Line Items]
Hurdle Value	$ 265,158	$ 234,834
Hurdle Value Two [Member]
Limited Liability Company LLC Members Equity [Line Items]
Hurdle Value	346,107	306,706
Hurdle Value Three [Member]
Limited Liability Company LLC Members Equity [Line Items]
Hurdle Value	386,277	$ 342,451
Profits Interest [Member] | Hurdle Value One [Member]
Limited Liability Company LLC Members Equity [Line Items]
Hurdle Value	265,158
Profits Interest [Member] | Hurdle Value Two [Member]
Limited Liability Company LLC Members Equity [Line Items]
Hurdle Value	346,107
Profits Interest [Member] | Hurdle Value Three [Member]
Limited Liability Company LLC Members Equity [Line Items]
Hurdle Value	$ 386,277

Members' Deficit - Additional I

Members' Deficit - Additional Information (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ / shares in Units, $ in Thousands	Apr. 27, 2020	Jun. 30, 2020	Jun. 30, 2020
Limited Liability Company LLC Members Equity [Line Items]
Tender Offer Expiration Date	Apr. 27, 2020
Limited Liability Company (LLC) Common Unit Tendered Value	$ 20,000		$ 20,000
Limited Liability Company (LLC) Common Units, Price Per Unit	$ 156.29
Threshold Percentage On Transfer Of Common Units	10.00%
Repurchase Of Units During The Period Tender Offer Value		$ (19,393)	(19,393)
Additional Compensation Expense			606
Accumulated Deficit [Member]
Limited Liability Company LLC Members Equity [Line Items]
Repurchase Of Units During The Period Tender Offer Value			13,498
Member Units [Member]
Limited Liability Company LLC Members Equity [Line Items]
Repurchase Of Units During The Period Tender Offer Value		$ (5,895)	$ (5,895)

Unit-Based Compensation - Summa

Unit-Based Compensation - Summary of Unit-Based Compensation Awards Valuation Assumptions (Detail) - OAK Street Health L L C And Affiliates [Member]	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Risk-Free Rate	0.16%	1.58%
Volatility	65.00%	35.00%
Time to Liquidity Event (Years)	2 years	2 years 2 months 8 days

Unit-Based Compensation - Sum_2

Unit-Based Compensation - Summary of Profits Interests Award Activity (Detail) - OAK Street Health LLC and Affiliates [Member] $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	1,910,796	1,454,148
Beginning balance-Weighted Average Grant Date Fair Value | $ / shares	$ 12.68	$ 2.35
Granted-Profits Interests	1,095,067	496,763
Granted- Weighted Average Grant Date Fair Value | $ / shares	$ 53.51	$ 42.35
Vested-Profits Interests	188,381	193,375
Vested- Weighted Average Grant Date Fair Value | $ / shares	$ 5.09	$ 2.32
Forfeited/Repurchased	(56,121)	(40,115)
Forfeited/Repurchased- Weighted Average Grant Date Fair Value | $ / shares	$ 10.01	$ 5.74
Ending balance-Profits Interests	2,949,742	1,910,796
Ending balance- Weighted Average Grant Date Fair Value | $ / shares	$ 11.32	$ 12.68
Vested outstanding -Profits Interests	550,698	389,531
Hurdle Value One [Member]
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	111,076
Ending balance-Profits Interests	93,455	111,076
Hurdle Value | $	$ 265,158	$ 234,834
Hurdle Value Two [Member]
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	160,492
Ending balance-Profits Interests	151,370	160,492
Hurdle Value | $	$ 346,107	$ 306,706
Hurdle Value Three [Member]
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	45,275
Ending balance-Profits Interests	43,780	45,275
Hurdle Value | $	$ 386,277	$ 342,451
Hurdle Value Four [Member]
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	265,374
Ending balance-Profits Interests	253,874	265,374
Hurdle Value | $	$ 685,350	$ 608,955
Hurdle Value Five [Member]
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	462,292
Ending balance-Profits Interests	510,450	462,292
Hurdle Value | $	$ 782,361	$ 645,000
Hurdle Value Six [Member]
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	521,225
Ending balance-Profits Interests	458,090	521,225
Hurdle Value | $	$ 922,500	$ 697,700
Hurdle Value Seven [Member]
Unit Based Compensation Disclosure [Line Items]
Beginning balance-Profits Interests	345,062
Ending balance-Profits Interests	343,656	345,062
Hurdle Value | $	$ 1,582,500	$ 1,310,000
Hurdle Value Eight [Member]
Unit Based Compensation Disclosure [Line Items]
Ending balance-Profits Interests	380,250
Hurdle Value | $	$ 2,200,000
Hurdle Value Nine [Member]
Unit Based Compensation Disclosure [Line Items]
Ending balance-Profits Interests	714,817
Hurdle Value | $	$ 2,210,000

Unit-Based Compensation- Additi

Unit-Based Compensation- Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Unit Based Compensation Disclosure [Line Items]
Equity Instruments Other Than Options Grants In Period			1,095,067		496,763
Unit-Based Compensation	$ 3,461	$ 412	$ 5,289	$ 637
Profits Interest Award [Member]
Unit Based Compensation Disclosure [Line Items]
Unit-Based Compensation	3,502	$ 543	5,380	$ 799
Service Vesting Awards [Member]
Unit Based Compensation Disclosure [Line Items]
Unrecognized compensation expense	56,571		$ 56,571
Unrecognized compensation expense, period of recognition			1 year 8 months 4 days
Performance Vesting units [Member]
Unit Based Compensation Disclosure [Line Items]
Unrecognized compensation expense	$ 15,778		$ 15,778
Equity Incentive Plan 2015 [Member]
Unit Based Compensation Disclosure [Line Items]
Unit Options Exercised			0		0
Unit Options Outstanding	2,000		2,000		2,000
Equity Incentive Plan 2015 [Member] | Profits Interest Award [Member]
Unit Based Compensation Disclosure [Line Items]
Number Of Shares Authorized	3,000,000		3,000,000
Equity Instruments Other Than Options Grants In Period	829,567	244,120	1,095,067	244,120

Commitments - Operating Leases

Commitments - Operating Leases - Additional Information (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Deferred Rent Liability	$ 13,015		$ 13,015		$ 12,901
General and Administrative Expense [Member]
Operating Rent Expense	$ 4,608	$ 2,765	$ 9,221	$ 5,444

Variable Interest Entities - Su

Variable Interest Entities - Summary of VIE Assets and Liabilities and Performance for the Physician Groups (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Variable Interest Entity [Line Items]
Total assets	$ 0		$ 0		$ 0
OAK Street Health LLC and Affiliates [Member]
Variable Interest Entity [Line Items]
Total assets	532,227		532,227		301,822
Total liabilities	388,539		388,539		326,061
Total revenues	214,382	$ 126,488	416,167	$ 243,865
Operating expenses:
Cost of care	316	905	1,780	1,755
Variable Interest Entity, Primary Beneficiary [Member] | OAK Street Health LLC and Affiliates [Member]
Variable Interest Entity [Line Items]
Total assets	363,307		363,307		252,629
Total liabilities	301,621		301,621		$ 230,527
Total revenues	210,314	125,215	408,778	242,591
Operating expenses:
Total operating expenses	168,843	92,806	315,566	177,451
Variable Interest Entity, Primary Beneficiary [Member] | OAK Street Health LLC and Affiliates [Member] | Medical Claims Expense [Member]
Operating expenses:
Cost of care	154,656	83,577	286,032	160,271
Variable Interest Entity, Primary Beneficiary [Member] | OAK Street Health LLC and Affiliates [Member] | Cost of Care, Excluding Depreciation and Amortization [Member]
Operating expenses:
Cost of care	$ 14,187	$ 9,229	$ 29,534	$ 17,180

Related Parties - Additional In

Related Parties - Additional Information (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($) $ in Thousands	Sep. 01, 2018	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Liability for unpaid claims		$ 235,856	$ 170,629	$ 235,856	$ 170,629	$ 170,629	$ 68,174
Fee For Service Revenue [Member]
Related Party Transaction [Line Items]
Due from related parties		58		58		66
Related party transaction other patient service revenue		93	219	184	424
Care Coordination Revenue [Member]
Related Party Transaction [Line Items]
Related party transaction other patient service revenue		715	573	1,407	1,145
Humana [Member]
Related Party Transaction [Line Items]
Revenue from related parties		97,367	75,731	193,854	149,413
Due from related parties		46,775		46,775		49,647
Due to related parties current		2,773		2,773		2,540
Due to related parties noncurrent		6,066		6,066		4,705
Related party transactions, medical claims expenses		63,973	50,771	123,818	99,372
Liability for unpaid claims		50,381		50,381		58,916
Payments for license fees		671	486	1,342	898
Operating lease payments		564	$ 383	1,063	$ 661
Deferred rent liability		1,074		1,074		1,034
Humana [Member] | License Fee [Member]
Related Party Transaction [Line Items]
Due to related parties current		3,339		3,339		2,753
Humana [Member] | Investor Units III-D [Member]
Related Party Transaction [Line Items]
Limited liability company (LLC) investor unit issued during the period	850,629
Limited liability company (LLC) investor unit value issued during the period	$ 50,000
Capital units value		$ 57,233		$ 57,233		$ 55,084

Net Loss Per Unit - Summary of

Net Loss Per Unit - Summary of Basic and Diluted Net Loss Per Common Unit (Detail) - OAK Street Health L L C And Affiliates [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Earnings Per Share, Basic and Diluted [Abstract]
Net loss attributable to the Company	$ (26,765)	$ (20,161)	$ (41,765)	$ (30,156)
Less: Undeclared and deemed dividends on Investor Units	(12,230)	(7,188)	(21,802)	(14,302)
Net loss attributable to common unitholders	$ (38,995)	$ (27,349)	$ (63,567)	$ (44,458)
Weighted average common units outstanding	537,654	620,068	578,861	620,068
Net loss attributable to common unitholders – basic and diluted	$ (72.53)	$ (44.11)	$ (109.81)	$ (71.70)	$ (21.10)
Potentially dilutive securities excluded from the computation of diluted net loss per unit [Abstract]
Total	2,951,742	1,677,091	2,951,742	1,677,091
Options To Purchase Incentive Units [Member]
Potentially dilutive securities excluded from the computation of diluted net loss per unit [Abstract]
Options to purchase Incentive Units	2,000	2,000	2,000	2,000
Profits Interests [Member]
Potentially dilutive securities excluded from the computation of diluted net loss per unit [Abstract]
Profits Interests	2,949,742	1,675,091	2,949,742	1,675,091

Pro Forma Information - Additio

Pro Forma Information - Additional Information (Detail) - OAK Street Health LLC and Affiliates [Member] - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Effective income tax rate	0.00%
Pro Forma [Member]
Effective income tax rate	25.00%	25.00%
Income tax expense	$ 0	$ 0

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Aug. 11, 2020	Aug. 10, 2020	Aug. 05, 2020	Aug. 31, 2020	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2020	Jul. 01, 2019	Apr. 26, 2019	Apr. 01, 2019	Aug. 07, 2017
Subsequent Event [Line Items]
Shares of common stock was declared effective					1,000		1,000
Common stock, par value					$ 0.001	$ 0.001	$ 0.001
Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member]
Subsequent Event [Line Items]
Debt instrument, face amount											$ 20,000
Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member]
Subsequent Event [Line Items]
Debt instrument maturity date							Jun. 1, 2022
Debt instrument end of term charge in percentage terms					5.95%
Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche One [Member]
Subsequent Event [Line Items]
Debt instrument, face amount										$ 30,000
Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche Two [Member]
Subsequent Event [Line Items]
Debt instrument, face amount									$ 30,000
Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche Three [Member]
Subsequent Event [Line Items]
Debt instrument, face amount								$ 20,000
Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche Four [Member]
Subsequent Event [Line Items]
Debt instrument, face amount								10,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Shares of common stock was declared effective		500,000,000
Common stock, par value		$ 0.001
Preferred stock, shares authorized		50,000,000
Preferred stock, par value		$ 0.001
Proceeds from issuance of initial public offering		$ 351,703
Payments for underwriting expense		22,641
Deferred offering costs		$ 3,000
Subsequent Event [Member] | Twenty Twenty Omnibus Incentive Plan [Member]
Subsequent Event [Line Items]
Share-based compensation arrangement by share-based payment award, effective date			Aug. 5, 2020
Share-based payment award, number of shares available for issuance			48,138,967
Share-based payment award, plan modification, description and terms			The Share Reserve will automatically increase on each January 1 that occurs after the August 5, 2020 effective date, for 10 years, by an amount equal to 5% of the total number of shares outstanding on December 31 of the preceding calendar year, or a lesser number as may be determined by the Board of Directors of the Company.
Share-based payment Award, percentage of outstanding stock maximum			5.00%
Share-based payment award, expiration period			10 years
Subsequent Event [Member] | Twenty Twenty Employee Stock Purchase Plan [Member]
Subsequent Event [Line Items]
Share-based payment award, number of shares available for issuance			2,386,875
Share-based payment Award, percentage of outstanding stock maximum			1.00%
Sharebased compensation arrangement by sharebased payment award payroll deduction percentage on employee subscription			15.00%
Sharebased compensation arrangement by sharebased payment award purchase price percentage applied on lower market price			85.00%
Subsequent Event [Member] | Twenty Twenty Employee Stock Purchase Plan [Member] | Maximum [Member]
Subsequent Event [Line Items]
Share-based payment award, number of shares available for issuance			30,000,000
Subsequent Event [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member]
Subsequent Event [Line Items]
Repayments of long term debt	$ 80,000
Debt instrument, interest rate	9.75%
Debt instrument, principal amount redemption percentage	107.00%
Debt instrument redemption expense	$ 3,204
Subsequent Event [Member] | IPO [Member]
Subsequent Event [Line Items]
Shares of common stock was declared effective			17,968,750
Common stock, par value			$ 0.001
Stock issued during period shares		17,968,750
Shares offering, price per share		$ 21
Subsequent Event [Member] | Over-Allotment Option [Member]
Subsequent Event [Line Items]
Stock issued during period shares		2,343,750
Subsequent Event [Member] | Common Stock [Member] | Oak Street Health LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				58,467,139
Subsequent Event [Member] | Common Stock [Member] | OSH Management Holdings LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				38,164,950
Subsequent Event [Member] | Common Stock Subject To Vesting [Member] | OSH Management Holdings LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				22,621,901
Subsequent Event [Member] | Common Stock Option To Purchase [Member] | OSH Management Holdings LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				14,316,334
Subsequent Event [Member] | General Atlantic LLC and Newlight Partners LP [Member] | Common Stock [Member] | Oak Street Health LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				126,278,767
OAK Street Health LLC and Affiliates [Member]
Subsequent Event [Line Items]
Common stock, par value					$ 0.01	$ 0.01	$ 0.01
Stock issued during period shares					1,471,623	25,518
Deferred offering costs		$ 3,000
Repayments of long term debt					$ 82,126	$ 62,840	$ 82,126
OAK Street Health LLC and Affiliates [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member]
Subsequent Event [Line Items]
Debt instrument, face amount											$ 20,000
OAK Street Health LLC and Affiliates [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member]
Subsequent Event [Line Items]
Debt instrument maturity date							Jun. 1, 2022
Debt instrument end of term charge in percentage terms					5.95%
OAK Street Health LLC and Affiliates [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche One [Member]
Subsequent Event [Line Items]
Debt instrument, face amount										$ 30,000
OAK Street Health LLC and Affiliates [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche Two [Member]
Subsequent Event [Line Items]
Debt instrument, face amount									$ 30,000
OAK Street Health LLC and Affiliates [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche Three [Member]
Subsequent Event [Line Items]
Debt instrument, face amount								20,000
OAK Street Health LLC and Affiliates [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member] | Debt Instrument Amendment Agreement One [Member] | Tranche Four [Member]
Subsequent Event [Line Items]
Debt instrument, face amount								$ 10,000
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Stock issued during period shares		17,968,750
Proceeds from issuance of initial public offering		$ 351,703
Payments for underwriting expense		22,641
Deferred offering costs		$ 3,000
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Twenty Twenty Omnibus Incentive Plan [Member]
Subsequent Event [Line Items]
Share-based compensation arrangement by share-based payment award, effective date			Aug. 5, 2020
Share-based payment award, number of shares available for issuance			26,250,709
Share-based payment award, plan modification, description and terms			The number of shares initially available for issuance will be increased on January 1 of each calendar year, for 10 years, by an amount equal to 5% of the total number of shares outstanding on December 31 of the preceding calendar year, or a lesser number as may be determined by the Board.
Share-based payment Award, percentage of outstanding stock maximum			5.00%
Share-based payment award, expiration period			10 years
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Twenty Twenty Employee Stock Purchase Plan [Member]
Subsequent Event [Line Items]
Share-based payment award, number of shares available for issuance			2,386,875
Share-based payment Award, percentage of outstanding stock maximum			1.00%
Sharebased compensation arrangement by sharebased payment award payroll deduction percentage on employee subscription			15.00%
Sharebased compensation arrangement by sharebased payment award purchase price percentage applied on lower market price			85.00%
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Twenty Twenty Employee Stock Purchase Plan [Member] | Maximum [Member]
Subsequent Event [Line Items]
Share-based payment award, number of shares available for issuance			30,000,000
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Hercules Capital Inc [Member] | Notes Payable, Other Payables [Member]
Subsequent Event [Line Items]
Repayments of long term debt	$ 80,000
Debt instrument, interest rate	9.75%
Debt instrument, principal amount redemption percentage	107.00%
Debt instrument redemption expense	$ 3,204
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | IPO [Member]
Subsequent Event [Line Items]
Shares of common stock was declared effective			17,968,750
Common stock, par value			$ 0.001
Stock issued during period shares		17,968,750
Shares offering, price per share		$ 21
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Over-Allotment Option [Member]
Subsequent Event [Line Items]
Stock issued during period shares		2,343,750
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Common Stock [Member] | Oak Street Health LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				58,467,139
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Common Stock [Member] | OSH Management Holdings LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				38,164,950
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Common Stock Subject To Vesting [Member] | OSH Management Holdings LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				22,621,901
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | Common Stock Option To Purchase [Member] | OSH Management Holdings LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				14,316,334
OAK Street Health LLC and Affiliates [Member] | Subsequent Event [Member] | General Atlantic LLC and Newlight Partners LP [Member] | Common Stock [Member] | Oak Street Health LLC [Member]
Subsequent Event [Line Items]
Business acquisition, equity interest issued or issuable, number of shares				126,278,767