Guarantor Financial Information (Consolidating Statements of Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Product sales									$ 14,448.9	$ 10,885.8	$ 6,099.9
Royalties and other revenues									711.7	510.8	316.8
Total revenues	$ 4,144.9	$ 3,697.6	$ 3,745.8	$ 3,572.3	$ 3,806.1	$ 3,452.1	$ 2,429.1	$ 1,709.3	15,160.6	11,396.6	6,416.7
Costs and expenses:
Cost of sales	1,263.5	1,001.4	1,108.9	1,327.0	1,053.6	1,736.2	778.1	248.6	4,700.8	3,816.5	969.0
Research and development									1,763.3	1,439.8	1,564.0
Selling, general and administrative									3,530.9	3,015.2	1,842.5
Amortization of acquired intangible assets									1,768.4	1,173.4	498.7
Integration and acquisition costs									894.5	883.9	39.8
Reorganization costs									47.9	121.4	97.9
Gain/(loss) on sale of product rights									(0.4)	(16.5)	(14.7)
Total operating expenses									12,705.4	10,433.7	4,997.2
Operating income from continuing operations									2,455.2	962.9	1,419.5
Interest income/(expense), net									(569.2)	(451.2)	(37.4)
Other income/(expense), net									7.4	(25.6)	3.7
Total other expense, net									(561.8)	(476.8)	(33.7)
Income from continuing operations before income taxes and equity in earnings/(losses) of equity method investees									1,893.4	486.1	1,385.8
Income taxes									2,357.6	126.1	(46.1)
Equity in income/(losses) of equity method investees, net of taxes									2.5	(8.7)	(2.2)
Income from continuing operations, net of taxes	3,106.0	551.2	241.5	354.8	475.9	(368.5)	86.6	409.5	4,253.5	603.5	1,337.5
Gain/(loss) from discontinued operations, net of taxes	(0.6)	(0.4)	(1.2)	20.2	(18.6)	(18.3)	(248.7)	9.5	18.0	(276.1)	(34.1)
Net income	$ 3,105.4	$ 550.8	$ 240.3	$ 375.0	$ 457.3	$ (386.8)	$ (162.1)	$ 419.0	4,271.5	327.4	1,303.4
Comprehensive income/(loss)									7,144.1	(986.4)	1,151.1
Eliminations
Revenues:
Product sales									0.0	0.0	0.0
Royalties and other revenues									0.0	0.0	0.0
Total revenues									0.0	0.0	0.0
Costs and expenses:
Cost of sales									0.0	0.0	0.0
Research and development									0.0	0.0	0.0
Selling, general and administrative									0.0	0.0	1.4
Amortization of acquired intangible assets									0.0	0.0	0.0
Integration and acquisition costs									0.0	0.0	0.0
Reorganization costs									0.0	0.0	0.0
Gain/(loss) on sale of product rights									0.0	0.0	0.0
Total operating expenses									0.0	0.0	1.4
Operating income from continuing operations									0.0	0.0	(1.4)
Interest income/(expense), net									0.0	0.0	0.0
Other income/(expense), net									0.0	0.0	0.0
Total other expense, net									0.0	0.0	0.0
Income from continuing operations before income taxes and equity in earnings/(losses) of equity method investees									0.0	0.0	(1.4)
Income taxes									0.0	0.0	0.0
Equity in income/(losses) of equity method investees, net of taxes									(6,158.4)	174.9	(1,388.1)
Income from continuing operations, net of taxes									(6,158.4)	174.9	(1,389.5)
Gain/(loss) from discontinued operations, net of taxes									0.0	0.0	0.0
Net income									(6,158.4)	174.9	(1,389.5)
Comprehensive income/(loss)									(11,621.8)	2,694.4	(1,237.2)
Shire plc (Parent Guarantor)
Revenues:
Product sales									0.0	0.0	0.0
Royalties and other revenues									0.0	0.0	0.0
Total revenues									0.0	0.0	0.0
Costs and expenses:
Cost of sales									0.0	0.0	0.0
Research and development									0.0	0.0	0.0
Selling, general and administrative									5.8	59.8	24.9
Amortization of acquired intangible assets									0.0	0.0	0.0
Integration and acquisition costs									168.2	0.0
Reorganization costs									0.0	0.0	0.0
Gain/(loss) on sale of product rights									0.0	0.0	0.0
Total operating expenses									174.0	59.8	24.9
Operating income from continuing operations									(174.0)	(59.8)	(24.9)
Interest income/(expense), net									(145.8)	(100.6)	(63.6)
Other income/(expense), net									2.2	0.9	0.9
Total other expense, net									(143.6)	(99.7)	(62.7)
Income from continuing operations before income taxes and equity in earnings/(losses) of equity method investees									(317.6)	(159.5)	(87.6)
Income taxes									3.5	4.3	2.9
Equity in income/(losses) of equity method investees, net of taxes									4,585.6	482.6	1,388.1
Income from continuing operations, net of taxes									4,271.5	327.4	1,303.4
Gain/(loss) from discontinued operations, net of taxes									0.0	0.0	0.0
Net income									4,271.5	327.4	1,303.4
Comprehensive income/(loss)									7,144.1	(986.4)	1,151.1
SAIIDAC (SAIIDAC Notes Subsidiary Issuer)
Revenues:
Product sales									0.0	0.0	0.0
Royalties and other revenues									0.0	0.0	0.0
Total revenues									0.0	0.0	0.0
Costs and expenses:
Cost of sales									0.0	0.0	0.0
Research and development									0.0	0.0	0.0
Selling, general and administrative									0.0	0.0	0.0
Amortization of acquired intangible assets									0.0	0.0	0.0
Integration and acquisition costs									0.0	0.0	0.0
Reorganization costs									0.0	0.0	0.0
Gain/(loss) on sale of product rights									0.0	0.0	0.0
Total operating expenses									0.0	0.0	0.0
Operating income from continuing operations									0.0	0.0	0.0
Interest income/(expense), net									3.6	36.5	(1.7)
Other income/(expense), net									0.0	0.0	0.0
Total other expense, net									3.6	36.5	(1.7)
Income from continuing operations before income taxes and equity in earnings/(losses) of equity method investees									3.6	36.5	(1.7)
Income taxes									(0.9)	(9.1)	0.0
Equity in income/(losses) of equity method investees, net of taxes									0.0	0.0	0.0
Income from continuing operations, net of taxes									2.7	27.4	(1.7)
Gain/(loss) from discontinued operations, net of taxes									0.0	0.0	0.0
Net income									2.7	27.4	(1.7)
Comprehensive income/(loss)									2.7	27.4	(1.7)
Baxalta Inc. (Baxalta Notes Subsidiary Issuer and SAIIDAC Notes Subsidiary Guarantor)
Revenues:
Product sales									0.0	0.0	0.0
Royalties and other revenues									0.0	0.0	0.0
Total revenues									0.0	0.0	0.0
Costs and expenses:
Cost of sales									0.0	0.0	0.0
Research and development									0.0	0.4	0.0
Selling, general and administrative									13.6	29.4	0.0
Amortization of acquired intangible assets									2.2	0.0	0.0
Integration and acquisition costs									110.6	302.0	0.0
Reorganization costs									0.0	0.0	0.0
Gain/(loss) on sale of product rights									0.0	0.0	0.0
Total operating expenses									126.4	331.8	0.0
Operating income from continuing operations									(126.4)	(331.8)	0.0
Interest income/(expense), net									(91.4)	(45.1)	0.0
Other income/(expense), net									4.4	2.7	0.0
Total other expense, net									(87.0)	(42.4)	0.0
Income from continuing operations before income taxes and equity in earnings/(losses) of equity method investees									(213.4)	(374.2)	0.0
Income taxes									7.5	88.9	0.0
Equity in income/(losses) of equity method investees, net of taxes									1,572.8	(657.5)	0.0
Income from continuing operations, net of taxes									1,366.9	(942.8)	0.0
Gain/(loss) from discontinued operations, net of taxes									0.0	0.0	0.0
Net income									1,366.9	(942.8)	0.0
Comprehensive income/(loss)									3,963.5	(2,148.9)	0.0
Non-Guarantor Non-Issuer Subsidiaries
Revenues:
Product sales									14,448.9	10,885.8	6,099.9
Royalties and other revenues									711.7	510.8	316.8
Total revenues									15,160.6	11,396.6	6,416.7
Costs and expenses:
Cost of sales									4,700.8	3,816.5	969.0
Research and development									1,763.3	1,439.4	1,564.0
Selling, general and administrative									3,511.5	2,926.0	1,816.2
Amortization of acquired intangible assets									1,766.2	1,173.4	498.7
Integration and acquisition costs									615.7	581.9	39.8
Reorganization costs									47.9	121.4	97.9
Gain/(loss) on sale of product rights									(0.4)	(16.5)	(14.7)
Total operating expenses									12,405.0	10,042.1	4,970.9
Operating income from continuing operations									2,755.6	1,354.5	1,445.8
Interest income/(expense), net									(335.6)	(342.0)	27.9
Other income/(expense), net									0.8	(29.2)	2.8
Total other expense, net									(334.8)	(371.2)	30.7
Income from continuing operations before income taxes and equity in earnings/(losses) of equity method investees									2,420.8	983.3	1,476.5
Income taxes									2,347.5	42.0	(49.0)
Equity in income/(losses) of equity method investees, net of taxes									2.5	(8.7)	(2.2)
Income from continuing operations, net of taxes									4,770.8	1,016.6	1,425.3
Gain/(loss) from discontinued operations, net of taxes									18.0	(276.1)	(34.1)
Net income									4,788.8	740.5	1,391.2
Comprehensive income/(loss)									7,655.6	(572.9)	1,238.9
Non-Guarantor Subsidiaries of Baxalta Notes
Revenues:
Product sales									14,448.9	10,885.8	6,099.9
Royalties and other revenues									711.7	510.8	316.8
Total revenues									15,160.6	11,396.6	6,416.7
Costs and expenses:
Cost of sales									4,700.8	3,816.5	969.0
Research and development									1,763.3	1,439.4	1,564.0
Selling, general and administrative									3,511.5	2,926.0	1,816.2
Amortization of acquired intangible assets									1,766.2	1,173.4	498.7
Integration and acquisition costs									615.7	581.9	39.8
Reorganization costs									47.9	121.4	97.9
Gain/(loss) on sale of product rights									(0.4)	(16.5)	(14.7)
Total operating expenses									12,405.0	10,042.1	4,970.9
Operating income from continuing operations									2,755.6	1,354.5	1,445.8
Interest income/(expense), net									(332.0)	(305.5)	26.2
Other income/(expense), net									0.8	(29.2)	2.8
Total other expense, net									(331.2)	(334.7)	29.0
Income from continuing operations before income taxes and equity in earnings/(losses) of equity method investees									2,424.4	1,019.8	1,474.8
Income taxes									2,346.6	32.9	(49.0)
Equity in income/(losses) of equity method investees, net of taxes									2.5	(8.7)	(2.2)
Income from continuing operations, net of taxes									4,773.5	1,044.0	1,423.6
Gain/(loss) from discontinued operations, net of taxes									18.0	(276.1)	(34.1)
Net income									4,791.5	767.9	1,389.5
Comprehensive income/(loss)									$ 7,658.3	$ (545.5)	$ 1,237.2