INTANGIBLE ASSETS AND GOODWILL (Details) - USD ($) $ in Millions	3 Months Ended						12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2015
Finite-lived intangible assets:
Weighted- Average Useful Lives (Years)							8 years
Gross Carrying Amount	$ 28,186.7			$ 14,430.9			$ 28,186.7
Accumulated Amortization, Including Impairments	(7,411.6)			(5,140.6)			(7,411.6)
Net Carrying Amount	20,775.1			9,290.3			20,775.1
Total intangible assets
Gross carrying amount	30,494.6			16,418.5			30,494.6
Intangible assets, net	23,083.0			11,277.9			23,083.0
Impairment of finite-lived intangible assets	79.0
Asset impairment charges	23.0
Ezogabine Retigabine
Total intangible assets
Impairment of finite-lived intangible assets	27.0
Zelapar
Total intangible assets
Impairment of finite-lived intangible assets		$ 26.0
Developed Markets | Ezogabine Retigabine
Total intangible assets
Impairment charges						$ 552.0
Non-recurring basis | Amortization and Impairments of Finite-lived Intangible Assets | Ezogabine Retigabine
Total intangible assets
Impairment charges						$ 552.0
Non-recurring basis | Amortization and Impairments of Finite-lived Intangible Assets | Developed Markets | Kinerase
Total intangible assets
Impairment charges				55.0
Non-recurring basis | Amortization and Impairments of Finite-lived Intangible Assets | Developed Markets | Grifulvin
Total intangible assets
Impairment charges					$ 32.0
Acquired IPR&D
Finite-lived intangible assets:
Accumulated Amortization, Including Impairments	0.0			0.0			0.0
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	610.4			290.1			610.4
Corporate brands
Finite-lived intangible assets:
Accumulated Amortization, Including Impairments	0.0			0.0			0.0
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	1,697.5			1,697.5			$ 1,697.5
In Process Research and Development
Total intangible assets
Impairment of indefinite-lived intangible assets	28.0	$ 90.0	$ 12.0		$ 20.0
Product brands
Finite-lived intangible assets:
Weighted- Average Useful Lives (Years)							9 years
Gross Carrying Amount	22,082.8			10,320.1			$ 22,082.8
Accumulated Amortization, Including Impairments	(5,236.4)			(3,579.8)			(5,236.4)
Net Carrying Amount	16,846.4			6,740.3			$ 16,846.4
Corporate brands
Finite-lived intangible assets:
Weighted- Average Useful Lives (Years)							17 years
Gross Carrying Amount	1,066.1			366.1			$ 1,066.1
Accumulated Amortization, Including Impairments	(107.1)			(65.2)			(107.1)
Net Carrying Amount	959.0			300.9			$ 959.0
Product rights
Finite-lived intangible assets:
Weighted- Average Useful Lives (Years)							8 years
Gross Carrying Amount	4,339.9			3,225.9			$ 4,339.9
Accumulated Amortization, Including Impairments	(1,711.7)			(1,263.8)			(1,711.7)
Net Carrying Amount	2,628.2			1,962.1			$ 2,628.2
Partner relationships
Finite-lived intangible assets:
Weighted- Average Useful Lives (Years)							3 years
Gross Carrying Amount	217.6			236.8			$ 217.6
Accumulated Amortization, Including Impairments	(170.3)			(107.5)			(170.3)
Net Carrying Amount	47.3			129.3			$ 47.3
Technology and other
Finite-lived intangible assets:
Weighted- Average Useful Lives (Years)							7 years
Gross Carrying Amount	480.3			282.0			$ 480.3
Accumulated Amortization, Including Impairments	(186.1)			(124.3)			(186.1)
Net Carrying Amount	$ 294.2			$ 157.7			$ 294.2