Related Party Transactions (Narrative) (Details) $ in Thousands		9 Months Ended
	Jan. 01, 2022 $ / employee	Dec. 31, 2021 USD ($) $ / employee	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)
Related Party Transaction [Line Items]
Long-term debt, excluding current portion		$ 4,572,865		$ 4,734,775
Employer Healthcare Program Agreement [Member]
Related Party Transaction [Line Items]
Service fee per participating employee per month | $ / employee		3.00
Option Agreement [Member[ | McKesson Corporation [Member]
Related Party Transaction [Line Items]
Maximum percentage of ownership in the outstanding units of the Joint Venture allowed for option to acquire can be exercised		5.00%
Transition Services Agreements [Member]
Related Party Transaction [Line Items]
Transition fee income			$ 283
Senior Credit Facilities [Member] | GSO-Managed Funds [Member]
Related Party Transaction [Line Items]
Long-term debt, excluding current portion		$ 252,131		$ 162,189
Subsequent Event [Member] | Employer Healthcare Program Agreement [Member]
Related Party Transaction [Line Items]
Service fee per participating employee per month | $ / employee	3.25