Goodwill Impairment Charges	9 Months Ended
Goodwill Impairment Charges	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill Impairment Charges	Goodwill Impairment Charges The Company evaluates goodwill for impairment on an annual basis and at an interim date, if indicators of potential impairment exist. On October 1, 2019, the Company voluntarily changed its annual goodwill impairment testing date from January 1 to October 1 to better align with the timing of the Company’s annual long-term planning process. Accordingly, management determined that the change in accounting principle is preferable under the circumstance. This change has been applied prospectively from October 1, 2019 as retrospective application is deemed impracticable due to the inability to objectively determine the assumptions and significant estimates used in earlier periods without the benefit of hindsight. This change was not material to the Company’s consolidated financial statements as it did not delay, accelerate, or avoid any potential goodwill impairment charge. The impairment testing performed in the nine months ended December 31, 2019 did not indicate any material impairment of goodwill. As discussed below, impairment testing performed in the nine months ended December 31, 2018 indicated impairment charges totaling $591 million (pre-tax and after-tax). Goodwill impairment testing is conducted at the reporting unit level, which is generally defined as an operating segment or one level below an operating segment (also known as a component), for which discrete financial information is available and segment management regularly reviews the operating results of that reporting unit. 2019 First and Third Quarters In the first quarter of 2019, the Company recorded non-cash goodwill impairment charges of $570 million (pre-tax and after-tax) for its two reporting units in the European Pharmaceutical Solutions segment. During the third quarter of 2019, the Company recorded a non-cash goodwill impairment charge of $21 million (pre-tax and after-tax) for its Rexall Health reporting unit, included in Other. These charges were recorded under the caption, “Goodwill Impairment Charges” within operating expenses in the condensed consolidated statements of operations. Prior to implementing the current segment reporting structure in the first quarter of 2019, the Company’s European operations were considered a single reporting unit. Following the change in reportable segments, the Company’s European Pharmaceutical Solutions segment was split into two distinct reporting units, Retail Pharmacy and Pharmaceutical Distribution (formerly known as “Consumer Solutions” and “Pharmacy Solutions”) for purposes of goodwill impairment testing. As a result, the Company was required to perform a goodwill impairment test for these two new reporting units upon the change in reportable segments. Consequently, the Company recorded a non-cash goodwill impairment charge of $238 million (pre-tax and after-tax) in the first quarter of 2019 primarily because the estimated fair value of the Pharmaceutical Distribution reporting unit was determined to be lower than its reassigned carrying value. During the first quarter of 2019, both reporting units projected a decline in the estimated future cash flows primarily triggered by additional U.K. government actions which were announced on June 29, 2018. Accordingly, the Company performed an interim goodwill impairment test for these reporting units. As a result, the Company determined that the carrying values of these reporting units exceeded their estimated fair values and recorded non-cash goodwill impairment charges of $332 million (pre-tax and after-tax), primarily for its Retail Pharmacy reporting unit. The discount rate and terminal growth rate used for the Retail Pharmacy reporting unit in the first quarter 2019 impairment test were 8.5% and 1.25%. The discount rate and terminal growth rate used for the Pharmaceutical Distribution reporting unit in the first quarter 2019 impairment test were 8.0% and 1.25%. As previously disclosed in the Company’s 2019 Annual Report, as of March 31, 2019 the entire remaining goodwill balances of both reporting units were impaired. Refer to Financial Note 15, “Fair Value Measurements,” for more information on nonrecurring fair value measurements.