SEGMENT INFORMATION (Details) $ in Millions	3 Months Ended									6 Months Ended		9 Months Ended		12 Months Ended			29 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2013 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 USD ($)
Segment reporting information
Number of reportable segments | segment														2
Number of operating segments | segment														2
Total revenues	$ 2,757.2	$ 2,786.8	$ 2,732.4	$ 2,170.1	$ 2,235.4	$ 2,043.3	$ 2,041.1	$ 1,886.2		$ 4,902.5	$ 3,927.3	$ 7,689.3	$ 5,970.6	$ 10,446.5	$ 8,206.0	$ 5,769.6
Total segment profit														(287.8)	879.4	(863.6)
Restructuring, integration and other costs														(361.9)	(381.7)	(462.0)
In-process research and development impairments and other charges														(248.4)	(41.0)	(153.6)
Acquisition-related costs														(38.5)	(6.3)	(36.4)
Acquisition-related contingent consideration														23.0	14.1	29.2
Other (expense) income														(256.1)	268.7	(287.2)
Operating income (loss)	167.1	$ 447.8	$ 341.5	$ 571.0	617.4	$ 671.6	$ 355.1	356.6		$ 912.5	$ 711.7	$ 1,360.3	$ 1,383.3	1,527.4	2,000.7	(409.5)
Interest income														3.3	5.0	8.0
Interest expense														(1,563.2)	(971.0)	(844.3)
Loss on extinguishment of debt								$ (94.0)						(20.0)	(129.6)	(65.0)
Foreign exchange and other														(102.8)	(144.1)	(9.4)
Gain on investments, net														0.0	292.6	5.8
(Loss) Income before provision for (recovery of) income taxes														(155.3)	1,053.6	(1,314.4)
Stock-based compensation expense														95.0	40.0	46.0
Total assets	48,964.5				26,304.7									48,964.5	26,304.7	27,932.9	$ 48,964.5
Capital Expenditures, and Depreciation and Amortization
Total capital expenditures														235.2	291.6	115.3
Total depreciation and amortization, including impairments of finite-lived intangible assets														2,627.5	1,737.6	2,015.8
2015 Acquisitions
Segment reporting information
Acquisition-related costs														(16.0)
B&L
Segment reporting information
Restructuring, integration and other costs														(5.1)	(69.7)	(234.1)
Acquisition-related costs																	(13.0)
Developed Markets
Segment reporting information
Total revenues														8,537.3	6,109.6	4,293.2
Total segment profit														2,463.8	1,980.7	573.2
Total assets	41,182.7				19,070.8									41,182.7	19,070.8	20,007.2	41,182.7
Capital Expenditures, and Depreciation and Amortization
Total capital expenditures														190.7	152.7	54.1
Total depreciation and amortization, including impairments of finite-lived intangible assets														2,245.9	1,336.9	1,687.7
Developed Markets | Ezogabine Retigabine
Segment reporting information
Impairment charges on intangible assets									$ 552.0
Developed Markets | Fair Value Adjustment to Inventory and Identifiable Intangible Assets
Segment reporting information
Total segment profit														2,220.0	906.0	1,080.0
Developed Markets | 2014 and 2015 Acquisitions [Member]
Segment reporting information
Total revenues														2,120.0	1,700.0
Emerging Markets
Segment reporting information
Total revenues														1,909.2	2,096.4	1,476.4
Total segment profit														238.5	337.3	93.0
Total assets	6,897.4				6,332.9									6,897.4	6,332.9	6,907.8	6,897.4
Capital Expenditures, and Depreciation and Amortization
Total capital expenditures														26.9	29.3	51.9
Total depreciation and amortization, including impairments of finite-lived intangible assets														354.7	385.7	313.7
Emerging Markets | Fair Value Adjustment to Inventory and Identifiable Intangible Assets
Segment reporting information
Total segment profit														323.0	324.0	321.0
Emerging Markets | 2014 and 2015 Acquisitions [Member]
Segment reporting information
Total revenues														92.0	581.0
Total Segment
Segment reporting information
Total segment profit														2,702.3	2,318.0	666.2
Total assets	48,080.1				25,403.7									48,080.1	25,403.7	26,915.0	48,080.1
Capital Expenditures, and Depreciation and Amortization
Total capital expenditures														217.6	182.0	106.0
Total depreciation and amortization, including impairments of finite-lived intangible assets														2,600.6	1,722.6	2,001.4
Corporate
Segment reporting information
Total segment profit														(293.0)	(171.1)	(165.7)
Total assets	$ 884.4				$ 901.0									884.4	901.0	1,017.9	$ 884.4
Capital Expenditures, and Depreciation and Amortization
Total capital expenditures														17.6	109.6	9.3
Total depreciation and amortization, including impairments of finite-lived intangible assets														$ 26.9	$ 15.0	$ 14.4