Guarantor Financial Information (Consolidating Statements of Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Product sales	$ 3,808.6	$ 3,591.8	$ 7,445.7	$ 7,004.1
Royalties and other revenues	110.9	154.0	239.5	314.0
Total revenues	3,919.5	3,745.8	7,685.2	7,318.1
Costs and expenses:
Cost of sales	1,108.3	1,108.9	2,240.7	2,435.9
Research and development	427.6	542.4	832.8	921.7
Selling, general and administrative	907.7	899.1	1,712.5	1,788.0
Amortization of acquired intangible assets	457.6	434.1	941.6	798.1
Integration and acquisition costs	179.3	343.7	419.0	459.7
Reorganization costs	8.8	13.6	14.1	19.1
Gain/(loss) on sale of product rights	0.0	4.8	0.0	(0.7)
Total operating expenses	3,089.3	3,346.6	6,160.7	6,421.8
Operating income from continuing operations	830.2	399.2	1,524.5	896.3
Interest income/(expense), net	(125.0)	(140.2)	(249.4)	(279.4)
Other income/(expense), net	29.0	2.5	52.2	7.0
Total other expense, net	(96.0)	(137.7)	(197.2)	(272.4)
Income from continuing operations before income taxes and equity in earnings of equity method investees	734.2	261.5	1,327.3	623.9
Income taxes	(124.4)	(24.3)	(167.7)	(31.1)
Equity in income/(losses) of equity method investees, net of taxes	5.7	4.3	6.5	3.5
Income from continuing operations, net of taxes	615.5	241.5	1,166.1	596.3
Gain (loss) from discontinued operations, net of taxes	0.0	(1.2)	0.0	19.0
Net income	615.5	240.3	1,166.1	615.3
Comprehensive income/(loss)	(503.0)	1,667.5	518.7	2,313.0
Eliminations
Revenues:
Product sales	0.0	0.0	0.0	0.0
Royalties and other revenues	0.0	0.0	0.0	0.0
Total revenues	0.0	0.0	0.0	0.0
Costs and expenses:
Cost of sales	0.0	0.0	0.0	0.0
Research and development	0.0	0.0	0.0	0.0
Selling, general and administrative	0.0	0.0	0.0	0.0
Amortization of acquired intangible assets	0.0	0.0	0.0	0.0
Integration and acquisition costs	0.0	0.0	0.0	0.0
Reorganization costs	0.0	0.0	0.0	0.0
Gain/(loss) on sale of product rights		0.0		0.0
Total operating expenses	0.0	0.0	0.0	0.0
Operating income from continuing operations	0.0	0.0	0.0	0.0
Interest income/(expense), net	0.0	0.0	0.0	0.0
Other income/(expense), net	0.0	0.0	0.0	0.0
Total other expense, net	0.0	0.0	0.0	0.0
Income from continuing operations before income taxes and equity in earnings of equity method investees	0.0	0.0	0.0	0.0
Income taxes	0.0	0.0	0.0	0.0
Equity in income/(losses) of equity method investees, net of taxes	(1,030.3)	(525.7)	(1,721.8)	(816.7)
Income from continuing operations, net of taxes	(1,030.3)	(525.7)	(1,721.8)	(816.7)
Gain (loss) from discontinued operations, net of taxes		0.0		0.0
Net income	(1,030.3)	(525.7)	(1,721.8)	(816.7)
Comprehensive income/(loss)	1,174.4	(3,328.0)	(488.3)	(4,134.8)
Shire plc (Parent Guarantor)
Revenues:
Product sales	0.0	0.0	0.0	0.0
Royalties and other revenues	0.0	0.0	0.0	0.0
Total revenues	0.0	0.0	0.0	0.0
Costs and expenses:
Cost of sales	0.0	0.0	0.0	0.0
Research and development	0.0	0.0	0.0	0.0
Selling, general and administrative	79.0	8.7	90.9	18.1
Amortization of acquired intangible assets	0.0	0.0	0.0	0.0
Integration and acquisition costs	93.3	160.1	97.7	164.7
Reorganization costs	0.0	0.0	0.0	0.0
Gain/(loss) on sale of product rights		0.0		0.0
Total operating expenses	172.3	168.8	188.6	182.8
Operating income from continuing operations	(172.3)	(168.8)	(188.6)	(182.8)
Interest income/(expense), net	(34.4)	(30.8)	(66.7)	(61.1)
Other income/(expense), net	0.4	1.8	(0.2)	1.8
Total other expense, net	(34.0)	(29.0)	(66.9)	(59.3)
Income from continuing operations before income taxes and equity in earnings of equity method investees	(206.3)	(197.8)	(255.5)	(242.1)
Income taxes	16.3	(0.7)	17.2	0.8
Equity in income/(losses) of equity method investees, net of taxes	805.5	438.8	1,404.4	856.6
Income from continuing operations, net of taxes	615.5	240.3	1,166.1	615.3
Gain (loss) from discontinued operations, net of taxes		0.0		0.0
Net income	615.5	240.3	1,166.1	615.3
Comprehensive income/(loss)	(503.0)	1,667.5	518.7	2,313.0
SAIIDAC (SAIIDAC Notes Subsidiary Issuer)
Revenues:
Product sales	0.0	0.0	0.0	0.0
Royalties and other revenues	0.0	0.0	0.0	0.0
Total revenues	0.0	0.0	0.0	0.0
Costs and expenses:
Cost of sales	0.0	0.0	0.0	0.0
Research and development	0.0	0.0	0.0	0.0
Selling, general and administrative	0.0	0.0	0.0	0.0
Amortization of acquired intangible assets	0.0	0.0	0.0	0.0
Integration and acquisition costs	0.0	0.0	0.0	0.0
Reorganization costs	0.0	0.0	0.0	0.0
Gain/(loss) on sale of product rights		0.0		0.0
Total operating expenses	0.0	0.0	0.0	0.0
Operating income from continuing operations	0.0	0.0	0.0	0.0
Interest income/(expense), net	(3.4)	6.1	(7.8)	11.5
Other income/(expense), net	0.0	0.0	0.0	0.0
Total other expense, net	(3.4)	6.1	(7.8)	11.5
Income from continuing operations before income taxes and equity in earnings of equity method investees	(3.4)	6.1	(7.8)	11.5
Income taxes	1.9	(2.9)	3.0	(4.2)
Equity in income/(losses) of equity method investees, net of taxes	0.0	0.0	0.0	0.0
Income from continuing operations, net of taxes	(1.5)	3.2	(4.8)	7.3
Gain (loss) from discontinued operations, net of taxes		0.0		0.0
Net income	(1.5)	3.2	(4.8)	7.3
Comprehensive income/(loss)	(1.5)	3.2	(4.8)	7.3
Baxalta Inc. (Baxalta Notes Subsidiary Issuer and SAIIDAC Notes Subsidiary Guarantor)
Revenues:
Product sales	0.0	0.0	0.0	0.0
Royalties and other revenues	0.0	0.0	0.0	0.0
Total revenues	0.0	0.0	0.0	0.0
Costs and expenses:
Cost of sales	0.0	0.2	0.0	1.4
Research and development	0.0	0.0	0.0	0.0
Selling, general and administrative	4.3	4.2	7.2	9.9
Amortization of acquired intangible assets	0.0	0.0	0.0	0.0
Integration and acquisition costs	0.0	17.5	2.1	43.1
Reorganization costs	0.0	0.0	0.0	0.0
Gain/(loss) on sale of product rights		0.0		0.0
Total operating expenses	4.3	21.9	9.3	54.4
Operating income from continuing operations	(4.3)	(21.9)	(9.3)	(54.4)
Interest income/(expense), net	(33.2)	(21.5)	(54.5)	(42.9)
Other income/(expense), net	(1.1)	(0.6)	0.9	(0.1)
Total other expense, net	(34.3)	(22.1)	(53.6)	(43.0)
Income from continuing operations before income taxes and equity in earnings of equity method investees	(38.6)	(44.0)	(62.9)	(97.4)
Income taxes	8.8	(16.2)	13.2	(36.1)
Equity in income/(losses) of equity method investees, net of taxes	224.8	86.9	317.4	(39.9)
Income from continuing operations, net of taxes	195.0	26.7	267.7	(173.4)
Gain (loss) from discontinued operations, net of taxes		0.0		0.0
Net income	195.0	26.7	267.7	(173.4)
Comprehensive income/(loss)	(891.2)	1,401.8	(318.4)	1,450.5
Non-Guarantor Non-Issuer Subsidiaries
Revenues:
Product sales	3,808.6	3,591.8	7,445.7	7,004.1
Royalties and other revenues	110.9	154.0	239.5	314.0
Total revenues	3,919.5	3,745.8	7,685.2	7,318.1
Costs and expenses:
Cost of sales	1,108.3	1,108.7	2,240.7	2,434.5
Research and development	427.6	542.4	832.8	921.7
Selling, general and administrative	824.4	886.2	1,614.4	1,760.0
Amortization of acquired intangible assets	457.6	434.1	941.6	798.1
Integration and acquisition costs	86.0	166.1	319.2	251.9
Reorganization costs	8.8	13.6	14.1	19.1
Gain/(loss) on sale of product rights		4.8		(0.7)
Total operating expenses	2,912.7	3,155.9	5,962.8	6,184.6
Operating income from continuing operations	1,006.8	589.9	1,722.4	1,133.5
Interest income/(expense), net	(54.0)	(94.0)	(120.4)	(186.9)
Other income/(expense), net	29.7	1.3	51.5	5.3
Total other expense, net	(24.3)	(92.7)	(68.9)	(181.6)
Income from continuing operations before income taxes and equity in earnings of equity method investees	982.5	497.2	1,653.5	951.9
Income taxes	(151.4)	(4.5)	(201.1)	8.4
Equity in income/(losses) of equity method investees, net of taxes	5.7	4.3	6.5	3.5
Income from continuing operations, net of taxes	836.8	497.0	1,458.9	963.8
Gain (loss) from discontinued operations, net of taxes		(1.2)		19.0
Net income	836.8	495.8	1,458.9	982.8
Comprehensive income/(loss)	(281.7)	1,923.0	811.5	2,677.0
Non-Guarantor Subsidiaries of Baxalta Notes
Revenues:
Product sales	3,808.6	3,591.8	7,445.7	7,004.1
Royalties and other revenues	110.9	154.0	239.5	314.0
Total revenues	3,919.5	3,745.8	7,685.2	7,318.1
Costs and expenses:
Cost of sales	1,108.3	1,108.7	2,240.7	2,434.5
Research and development	427.6	542.4	832.8	921.7
Selling, general and administrative	824.4	886.2	1,614.4	1,760.0
Amortization of acquired intangible assets	457.6	434.1	941.6	798.1
Integration and acquisition costs	86.0	166.1	319.2	251.9
Reorganization costs	8.8	13.6	14.1	19.1
Gain/(loss) on sale of product rights		4.8		(0.7)
Total operating expenses	2,912.7	3,155.9	5,962.8	6,184.6
Operating income from continuing operations	1,006.8	589.9	1,722.4	1,133.5
Interest income/(expense), net	(57.4)	(87.9)	(128.2)	(175.4)
Other income/(expense), net	29.7	1.3	51.5	5.3
Total other expense, net	(27.7)	(86.6)	(76.7)	(170.1)
Income from continuing operations before income taxes and equity in earnings of equity method investees	979.1	503.3	1,645.7	963.4
Income taxes	(149.5)	(7.4)	(198.1)	4.2
Equity in income/(losses) of equity method investees, net of taxes	5.7	4.3	6.5	3.5
Income from continuing operations, net of taxes	835.3	500.2	1,454.1	971.1
Gain (loss) from discontinued operations, net of taxes		(1.2)		19.0
Net income	835.3	499.0	1,454.1	990.1
Comprehensive income/(loss)	$ (283.2)	$ 1,926.2	$ 806.7	$ 2,684.3