Business Combinations (ViroPharrma,NPS Pharma, Meritage) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			0 Months Ended		11 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Jan. 24, 2014	Dec. 29, 2014	Feb. 18, 2015	Feb. 21, 2015
Non-current assets:
Goodwill	$ 2,474.9	$ 624.6	$ 644.5	$ 2,474.9
Pro Forma Information
Post acquisition unwind of inventory fair value adjustment included in consolidated statement of income	91.9	0	0
Integration and acquisition costs	158.8	(134.1)	13.5
Minimum
Pro Forma Information
Estimated useful life of intangible assets	4 years
Maximum
Pro Forma Information
Estimated useful life of intangible assets	23 years
Viropharma
Business Acquisition [Line Items]
Percentage of voting interests acquired	100.00%			100.00%
Cash consideration paid				3,997.0	3,997.0
Expected operational synergies that will result from combining the commercial operations of Viropharma with those of Shire	400.0
Current assets:
Cash and cash equivalents	232.6			232.6	232.6
Short term investments	57.8			57.8	57.8
Accounts receivable	52.2			52.2	52.2
Inventories	203.6			203.6	203.5
Deferred tax assets	100.7			100.7	100.2
Purchased call option	346.7			346.7	346.7
Other current assets	50.9			50.9	42.5
Total current assets	1,044.5			1,044.5	1,035.5
Non-current assets:
Property, plant and equipment	24.7			24.7	24.7
Goodwill	1,655.5			1,655.5	1,536.6
Other non-current assets	10.4			10.4	11.6
Total assets	5,370.1			5,370.1	5,458.4
Current liabilities:
Accounts payable and other current liabilities	122.7			122.7	116.6
Convertible bond	551.4			551.4	551.4
Non-current liabilities:
Deferred tax liabilities	603.5			603.5	695.9
Other non-current liabilities	95.5			95.5	97.5
Total liabilities	1,373.1			1,373.1	1,461.4
Fair value of identified assets acquired and liabilities assumed	3,997.0			3,997.0	3,997.0
Pro Forma Information
Post acquisition revenues included in consolidated statement of income	538.1
Post acquisition pre-tax losses included in consolidated statement of income	77.8
Post acquisition amortization of intangible assets included in consolidated statement of income	106.6
Post acquisition unwind of inventory fair value adjustment included in consolidated statement of income	91.9
Post acquisition integration costs included in consolidated statement of income	101.1
Discount rate used in determining fair value of acquired in process research and development, low rate	9.50%			9.50%
Discount rate used in determining fair value of acquired in process research and development, high rate	10.00%			10.00%
Integration and acquisition costs	135.5	12.8
Viropharma | Measurement period adjustments
Current assets:
Inventories						0.1
Deferred tax assets						0.5
Other current assets						8.4
Total current assets						9.0
Non-current assets:
Goodwill						118.9
Other non-current assets						(1.2)
Total assets						(88.3)
Current liabilities:
Accounts payable and other current liabilities						6.1
Non-current liabilities:
Deferred tax liabilities						(92.4)
Other non-current liabilities						(2.0)
Total liabilities						(88.3)
Viropharma | Currently Marketed Products
Non-current assets:
Other intangible assets, net	2,320.0			2,320.0	2,320.0
Pro Forma Information
Weighted average amortization period of acquired amortizable intangible assets				22 years
Viropharma | Currently Marketed Products | Minimum
Pro Forma Information
Estimated useful life of intangible assets				10 years
Viropharma | Currently Marketed Products | Maximum
Pro Forma Information
Estimated useful life of intangible assets				23 years
Viropharma | IPR&D
Non-current assets:
Other intangible assets, net	315.0			315.0	530.0
Viropharma | IPR&D | Measurement period adjustments
Non-current assets:
Other intangible assets, net						(215.0)
Viropharma | IPR&D | VP20621
Measurement period Information
Other intangible assets, measurement period adjustment						(215.0)
Deferred tax liabilities, meaurement period adjustment						(80.2)
Goodwill, measurement period adjustment						134.8
NPS Pharma | NPS Pharma Acquisition
Business Acquisition [Line Items]
Percentage of voting interests acquired								100.00%
Purchase price paid per share of acquiree (in USD per share)								$ 46
Cash consideration payable in business acquisition								5,200
Meritage | Meritage Acquisition
Business Acquisition [Line Items]
Cash consideration paid							69.9
Maximum amount of contingent cash consideration							$ 175.0