Acquisitions and Investments	3 Months Ended
Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions and Investments	Acquisitions and Investments NEVSCO In December 2017, the Company acquired Northeast Veterinary Supply Company ("NEVSCO") for $70.0 million. NEVSCO was an independent, regional distributor of veterinary pharmaceuticals and medical supplies serving primarily the northeast region of the United States and strengthens MWI Animal Health's ("MWI") support of independent veterinary practices and provides even greater value and care to current and future animal health customers. NEVSCO is included within the MWI operating segment. The purchase price was allocated to the underlying assets acquired and liabilities assumed based upon their fair values on the date of the acquisition. The purchase price exceeded the fair value of the net tangible and intangible assets acquired by $30.4 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, and accounts payable and accrued expenses acquired was $8.5 million, $6.7 million, and $2.9 million, respectively. The fair value of the intangible assets acquired of $29.8 million primarily consisted of customer relationships, which the Company is amortizing over its estimated useful life of 15 years. Goodwill and intangible assets resulting from the acquisition are deductible for income tax purposes. H.D. Smith In January 2018, the Company acquired H.D. Smith Holding Company ("H.D. Smith") for $815.0 million. The Company funded the acquisition through the issuance of new long-term debt (see Note 6). H.D. Smith was the largest independent pharmaceutical wholesaler in the United States and provides full-line distribution of brand, generic, and specialty drugs, as well as high-value services and solutions for manufacturers and healthcare providers. H.D. Smith's customers include retail pharmacies, specialty pharmacies, long-term care facilities, institutional/hospital systems, and independent physicians and clinics. The acquisition strengthens the Company's core business, expands and enhances its strategic scale in pharmaceutical distribution, and expands the Company's support for independent community pharmacies. H.D. Smith is included within the Pharmaceutical Distribution reportable segment. The purchase price was allocated to the underlying assets acquired and liabilities assumed based upon their fair values on the date of the acquisition. The purchase price exceeded the fair value of the net tangible and intangible assets acquired by $499.9 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, and accounts payable and accrued expenses acquired was $163.1 million, $350.7 million, and $366.1 million, respectively. The fair value of the intangible assets acquired of $167.8 million consisted of customer relationships of $156.6 million and a tradename of $11.2 million. The Company is amortizing the fair value of the customer relationships and the tradename over their estimated useful lives of 12 years and 2 years, respectively. The Company established a deferred tax liability of $60.6 million primarily in connection with the intangible assets acquired. Goodwill and intangible assets resulting from the acquisition are not deductible for income tax purposes. Profarma and Specialty Joint Venture As of September 30, 2017, the Company held a noncontrolling ownership interest in Profarma Distribuidora de Produtos Farmacêuticos S.A. ("Profarma"), a leading pharmaceutical wholesaler in Brazil, and an ownership interest in a joint venture with Profarma to provide specialty distribution and services to the Brazilian marketplace (the "specialty joint venture"). The Company had accounted for these interests as equity method investments, which were reported in Other Assets on the Company's Consolidated Balance Sheets. In January 2018, the Company invested an additional $62.5 million in Profarma and an additional $15.6 million in the specialty joint venture to increase its ownership interests to 38.2% and 64.5%, respectively. In connection with the additional investment in Profarma, the Company received substantial governance rights, thereby requiring it to begin consolidating the operating results of Profarma as of March 31, 2018 (see Note 3). The Company also began to consolidate the operating results of the specialty joint venture as of March 31, 2018 due to its majority ownership interest. In September 2018, the Company made an additional investment of $23.6 million in the specialty joint venture to increase its ownership interest to 89.9%. Profarma and the specialty joint venture are included within the Pharmaceutical Distribution reportable segment and Other, respectively. The fair value of Profarma, including the noncontrolling interest, was determined based upon an agreed-upon stock price and was allocated to the underlying assets and liabilities consolidated based upon their fair values at the time of the January 2018 investment. The fair value of Profarma upon obtaining control exceeded the fair value of the net tangible and intangible assets consolidated by $142.0 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, accounts payable and accrued expenses was $160.1 million, $190.5 million, and $167.7 million, respectively. The Company consolidated short-term debt and long-term debt of $209.9 million and $12.4 million, respectively, cash of $150.8 million, and recorded a noncontrolling interest of $168.0 million. The estimated fair value of the intangible assets consolidated of $84.6 million consisted of customer relationships of $25.9 million and a tradename of $58.7 million. The Company is amortizing the customer relationships over its estimated useful life of 15 years and the tradenames over their estimated useful lives of between 15 years and 25 years. The Company established a deferred tax liability of $50.1 million primarily in connection with the intangible assets that were recognized. Goodwill and intangible assets resulting from the consolidation are not deductible for income tax purposes. The fair value of the specialty joint venture was determined based upon the cost of the incremental ownership percentage acquired from the January 2018 investment and was allocated to the underlying assets and liabilities consolidated based upon their fair values at the time of the January 2018 investment. The fair value of the specialty joint venture exceeded the fair value of the net tangible and intangible assets consolidated by $3.5 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, accounts payable and accrued expenses was $65.0 million, $29.1 million, and $54.3 million, respectively. The Company consolidated short-term debt and cash of $32.7 million and $28.9 million, respectively. The estimated fair value of the intangible assets consolidated of $4.6 million is being amortized over its estimated useful life of 15 years. Goodwill and intangible assets resulting from the consolidation are not deductible for income tax purposes.

Acquisitions and Investments

NEVSCO

In December 2017, the Company acquired Northeast Veterinary Supply Company ("NEVSCO") for $70.0 million. NEVSCO was an independent, regional distributor of veterinary pharmaceuticals and medical supplies serving primarily the northeast region of the United States and strengthens MWI Animal Health's ("MWI") support of independent veterinary practices and provides even greater value and care to current and future animal health customers. NEVSCO is included within the MWI operating segment.

The purchase price was allocated to the underlying assets acquired and liabilities assumed based upon their fair values on the date of the acquisition. The purchase price exceeded the fair value of the net tangible and intangible assets acquired by $30.4 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, and accounts payable and accrued expenses acquired was $8.5 million, $6.7 million, and $2.9 million, respectively. The fair value of the intangible assets acquired of $29.8 million primarily consisted of customer relationships, which the Company is amortizing over its estimated useful life of 15 years. Goodwill and intangible assets resulting from the acquisition are deductible for income tax purposes.

H.D. Smith

In January 2018, the Company acquired H.D. Smith Holding Company ("H.D. Smith") for $815.0 million. The Company funded the acquisition through the issuance of new long-term debt (see Note 6). H.D. Smith was the largest independent pharmaceutical wholesaler in the United States and provides full-line distribution of brand, generic, and specialty drugs, as well as high-value services and solutions for manufacturers and healthcare providers. H.D. Smith's customers include retail pharmacies, specialty pharmacies, long-term care facilities, institutional/hospital systems, and independent physicians and clinics. The acquisition strengthens the Company's core business, expands and enhances its strategic scale in pharmaceutical distribution, and expands the Company's support for independent community pharmacies. H.D. Smith is included within the Pharmaceutical Distribution reportable segment.

The purchase price was allocated to the underlying assets acquired and liabilities assumed based upon their fair values on the date of the acquisition. The purchase price exceeded the fair value of the net tangible and intangible assets acquired by $499.9 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, and accounts payable and accrued expenses acquired was $163.1 million, $350.7 million, and $366.1 million, respectively. The fair value of the intangible assets acquired of $167.8 million consisted of customer relationships of $156.6 million and a tradename of $11.2 million. The Company is amortizing the fair value of the customer relationships and the tradename over their estimated useful lives of 12 years and 2 years, respectively. The Company established a deferred tax liability of $60.6 million primarily in connection with the intangible assets acquired. Goodwill and intangible assets resulting from the acquisition are not deductible for income tax purposes.

Profarma and Specialty Joint Venture

As of September 30, 2017, the Company held a noncontrolling ownership interest in Profarma Distribuidora de Produtos Farmacêuticos S.A. ("Profarma"), a leading pharmaceutical wholesaler in Brazil, and an ownership interest in a joint venture with Profarma to provide specialty distribution and services to the Brazilian marketplace (the "specialty joint venture"). The Company had accounted for these interests as equity method investments, which were reported in Other Assets on the Company's Consolidated Balance Sheets. In January 2018, the Company invested an additional $62.5 million in Profarma and an additional $15.6 million in the specialty joint venture to increase its ownership interests to 38.2% and 64.5%, respectively. In connection with the additional investment in Profarma, the Company received substantial governance rights, thereby requiring it to begin consolidating the operating results of Profarma as of March 31, 2018 (see Note 3). The Company also began to consolidate the operating results of the specialty joint venture as of March 31, 2018 due to its majority ownership interest. In September 2018, the Company made an additional investment of $23.6 million in the specialty joint venture to increase its ownership interest to 89.9%. Profarma and the specialty joint venture are included within the Pharmaceutical Distribution reportable segment and Other, respectively.

The fair value of Profarma, including the noncontrolling interest, was determined based upon an agreed-upon stock price and was allocated to the underlying assets and liabilities consolidated based upon their fair values at the time of the January 2018 investment. The fair value of Profarma upon obtaining control exceeded the fair value of the net tangible and intangible assets consolidated by $142.0 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, accounts payable and accrued expenses was $160.1 million, $190.5 million, and $167.7 million, respectively. The Company consolidated short-term debt and long-term debt of $209.9 million and $12.4 million, respectively, cash of $150.8 million, and recorded a noncontrolling interest of $168.0 million. The estimated fair value of the intangible assets consolidated of $84.6 million consisted of customer relationships of $25.9 million and a tradename of $58.7 million. The Company is amortizing the customer relationships over its estimated useful life of 15 years and the tradenames over their estimated useful lives of between 15 years and 25 years. The Company established a deferred tax liability of $50.1 million primarily in connection with the intangible assets that were recognized. Goodwill and intangible assets resulting from the consolidation are not deductible for income tax purposes.

The fair value of the specialty joint venture was determined based upon the cost of the incremental ownership percentage acquired from the January 2018 investment and was allocated to the underlying assets and liabilities consolidated based upon their fair values at the time of the January 2018 investment. The fair value of the specialty joint venture exceeded the fair value of the net tangible and intangible assets consolidated by $3.5 million, which was allocated to goodwill. The fair value of accounts receivable, inventory, accounts payable and accrued expenses was $65.0 million, $29.1 million, and $54.3 million, respectively. The Company consolidated short-term debt and cash of $32.7 million and $28.9 million, respectively. The estimated fair value of the intangible assets consolidated of $4.6 million is being amortized over its estimated useful life of 15 years. Goodwill and intangible assets resulting from the consolidation are not deductible for income tax purposes.