Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense on property and equipment	$ 616,626	$ 600,905	$ 574,799
Capitalized interest	17,944	27,322	25,978
Other asset impairments	$ 0	$ 0	17,338
Pharmacy Business
Property, Plant and Equipment [Line Items]
Other asset impairments			$ 17,338
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Property, and equipment useful lives	25 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Property, and equipment useful lives	40 years
Leasehold Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, and equipment useful lives	10 years
Equipment and Information Systems | Minimum
Property, Plant and Equipment [Line Items]
Property, and equipment useful lives	3 years
Equipment and Information Systems | Maximum
Property, Plant and Equipment [Line Items]
Property, and equipment useful lives	15 years