CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions		3 Months Ended								5 Months Ended	7 Months Ended	12 Months Ended
		Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Aug. 10, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Total revenues		$ 577.7	$ 545.7	$ 523.7	$ 513.8	$ 394.1	$ 388.7	$ 353.1	$ 296.7			$ 2,160.9	$ 1,432.6	$ 882.8
Operating expenses:
Medical claims expense												1,645.0	1,109.0	617.8
Cost of care, excluding depreciation and amortization (Humana comprised $10.5 and $5.6 for the year ended December 31, 2021 and 2020, respectively)												437.8	293.7	187.5
Sales and marketing		43.8	44.1	42.6	33.8	38.9	30.5	25.9	24.1			164.3	119.4	64.2
Corporate, general and administrative		79.5	81.7	94.9	88.7	82.4	77.0	74.2	73.1			344.8	306.7	185.6
Depreciation and amortization												35.2	17.8	11.2
Total operating expenses												2,627.1	1,846.6	1,066.3
Loss from operations		(132.2)	(130.2)	(112.7)	(91.1)	(141.5)	(109.4)	(99.3)	(63.8)			(466.2)	(414.0)	(183.5)
Other (expense)/income:
Interest expense, net		(1.4)	0.0	(0.5)	(0.6)	(0.7)	(0.6)	(1.0)	(0.2)			(2.5)	(2.5)	(8.7)
Other		(0.5)	(0.2)	(35.1)	(5.0)	0.0	0.0	0.0	0.0			(40.8)	0.0	0.1
Total other (expense)		(1.9)	(0.2)	(35.6)	(5.6)	(0.7)	(0.6)	(1.0)	(0.2)			(43.3)	(2.5)	(8.6)
Loss before income taxes and non-controlling interests		(134.1)	(130.4)	(148.3)	(96.7)	(142.2)	(110.0)	(100.3)	(64.0)			(509.5)	(416.5)	(192.1)
Provision (benefit) for income taxes		0.2	0.0	0.0	0.0	(1.9)	0.0	0.0	0.0			0.2	(1.9)	0.0
Net loss		(134.3)	(130.4)	(148.3)	(96.7)	(140.3)	(110.0)	(100.3)	(64.0)			(509.7)	(414.6)	(192.1)
Net loss attributable to non-controlling interests		(1.4)	0.3	0.8	(0.2)	(1.7)	(0.6)	(2.3)	(0.6)			(0.5)	(5.2)	(4.1)
Net loss attributable to Oak Street Health, Inc.		$ (132.9)	$ (130.7)	$ (149.1)	$ (96.5)	$ (138.6)	$ (109.4)	$ (98.0)	$ (63.4)			(509.2)	(409.4)	(188.0)
Undeclared and deemed dividends											$ (27.2)	0.0	0.0	(27.2)
Net loss attributable to common stock/unitholders										$ (120.5)		$ (509.2)	$ (409.4)	$ (215.2)
Weighted average common stock outstanding - basic (in shares)	[1]											230,132,551	222,553,237	218,825,324
Weighted average common stock outstanding - diluted (in shares)	[1]											230,132,551	222,553,237	218,825,324
Net loss per share – basic (in dollars per share)		$ (0.56)	$ (0.56)	$ (0.66)	$ (0.43)	$ (0.62)	$ (0.49)	$ (0.44)	$ (0.29)			$ (2.21)	$ (1.84)	$ (0.55)
Net loss per share – diluted (in dollars per share)		$ (0.56)	$ (0.56)	$ (0.66)	$ (0.43)	$ (0.62)	$ (0.49)	$ (0.44)	$ (0.29)			$ (2.21)	$ (1.84)	$ (0.55)
Capitated Revenue
Total revenues		$ 565.8	$ 537.9	$ 516.1	$ 506.1	$ 382.4	$ 376.7	$ 346.7	$ 291.2			$ 2,125.9	$ 1,397.0	$ 851.3
Other revenue
Total revenues		$ 11.9	$ 7.8	$ 7.6	$ 7.7	$ 11.7	$ 12.0	$ 6.4	$ 5.5			$ 35.0	$ 35.6	$ 31.5

[1] Basic and diluted earnings per share of common stock is applicable only for periods after the Company's IPO that was completed on August 10, 2020.