Business Combinations (Details) $ / shares in Units, $ in Millions			3 Months Ended
	Jan. 22, 2016 USD ($) $ / shares	Feb. 21, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Jan. 11, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Contingent consideration payments			$ (2.1)	$ (2.4)
Integration and acquisition costs			91.1	75.7
Non-current assets:
Goodwill			6,881.9	4,178.7		$ 4,147.8	$ 2,474.9
Pro Forma Information
Post acquisition unwind of inventory fair value adjustment included in consolidated statement of income			12.8	11.2
Baxalta
Business Acquisition [Line Items]
Shire ADSs per Baxalta share					0.1482
Purchase price paid per share of acquiree, in cash (in USD per share) | $ / shares					$ 18
Purchase price paid per share of acquiree (in USD per share) | $ / shares					$ 45.57
Cash consideration payable in business acquisition					$ 32,000.0
Dyax
Business Acquisition [Line Items]
Contingent consideration payable, per share | $ / shares	$ 4
Purchase price paid per share of acquiree (in USD per share) | $ / shares	$ 37.3
Cash consideration paid	$ 5,934.0
Acquisition-date fair value of consideration	(6,330.0)
Maximum amount of contingent cash consideration	646.0
Fair value of contingent consideration payable	396.0
Integration and acquisition costs			51.7
Current assets:
Cash and cash equivalents	241.2
Accounts receivable,net	13.3
Inventories	20.2
Other current assets	8.1
Total current assets	282.8
Non-current assets:
Property, plant and equipment,net	5.8
Goodwill	2,729.5
Other non-current assets	28.3
Total assets	7,706.4
Current liabilities:
Accounts payable and other current liabilities	30.0
Other current liabilities	1.7
Non-current liabilities:
Deferred tax liabilities	1,343.3
Other non-current liabilities	1.4
Total liabilities	1,376.4
Fair value of identified assets acquired and liabilities assumed	$ (6,330.0)
Pro Forma Information
Post acquisition revenues included in consolidated statement of income			10.6
Post acquisition pre-tax losses included in consolidated statement of income			55.8
Post acquisition amortization of intangible assets included in consolidated statement of income			5.8
Post acquisition unwind of inventory fair value adjustment included in consolidated statement of income			1.1
Post acquisition integration costs included in consolidated statement of income			$ 21.0
Dyax | SHP643
Business Acquisition [Line Items]
Discount rate used in determining fair value of acquired in process research and development, high rate	9.00%
Dyax | KALBITOR
Business Acquisition [Line Items]
Estimated useful life of intangible assets	18 years
Dyax | Acquired intellectual property ("IP") rights for marketed products
Non-current assets:
Other intangible assets, net	$ 135.0
Dyax | IPR&D
Non-current assets:
Other intangible assets, net	4,100.0
Dyax | Royalty rights
Non-current assets:
Other intangible assets, net	$ 425.0
Dyax | Royalty rights | Minimum
Business Acquisition [Line Items]
Estimated useful life of intangible assets	7 years
Dyax | Royalty rights | Maximum
Business Acquisition [Line Items]
Estimated useful life of intangible assets	9 years
NPS Pharma
Business Acquisition [Line Items]
Percentage of voting interests acquired		100.00%
Cash consideration paid		$ 5,219.6
Acquisition-date fair value of consideration		5,219.6
Integration and acquisition costs				$ 75.7
Current assets:
Cash and cash equivalents		41.6
Short term investments		67.0
Accounts receivable,net		33.4
Inventories		89.4
Other current assets		11.1
Total current assets		242.5
Non-current assets:
Property, plant and equipment,net		4.8
Goodwill		1,551.0
Total assets		6,791.3
Current liabilities:
Accounts payable and other current liabilities		75.7
Short-term debt		27.4
Non-current liabilities:
Long term debt, less current portion		78.9
Deferred tax liabilities		1,385.2
Other non-current liabilities		4.5
Total liabilities		1,571.7
Fair value of identified assets acquired and liabilities assumed		5,219.6
NPS Pharma | Acquired intellectual property ("IP") rights for marketed products
Non-current assets:
Other intangible assets, net		$ 4,640.0
NPS Pharma | Acquired intellectual property ("IP") rights for marketed products | GATTEX/REVESTIVE
Business Acquisition [Line Items]
Estimated useful life of intangible assets		24 years
NPS Pharma | Acquired intellectual property ("IP") rights for marketed products | NATPARA/NATPAR
Business Acquisition [Line Items]
Estimated useful life of intangible assets		24 years
NPS Pharma | Royalty rights
Business Acquisition [Line Items]
Weighted average amortization period of acquired amortizable intangible assets		4 years
Non-current assets:
Other intangible assets, net		$ 353.0
NPS Pharma | Royalty rights | Minimum
Business Acquisition [Line Items]
Estimated useful life of intangible assets		4 years
NPS Pharma | Royalty rights | Maximum
Business Acquisition [Line Items]
Estimated useful life of intangible assets		5 years