Guarantor Financial Information (Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 317.7	$ 472.4	$ 369.0
Restricted cash	35.5	39.4	34.1
Accounts receivable, net	3,140.5	3,009.8
Inventories	3,340.8	3,291.5
Prepaid expenses and other current assets	1,080.5	795.3
Intercompany receivables	0.0	0.0
Short term intercompany loan receivable	0.0	0.0
Total current assets	7,915.0	7,608.4
Investments	271.8	241.1
Property, plant and equipment (PP&E), net	6,460.1	6,635.4
Goodwill	19,988.6	19,831.7	19,149.1	$ 17,888.2
Intangible assets, net	32,864.3	33,046.1	$ 32,834.1	$ 34,697.5
Deferred tax asset	189.2	188.8
Long term intercompany loan receivable	0.0	0.0
Other non-current assets	179.8	205.4
Total assets	67,868.8	67,756.9
Current liabilities:
Accounts payable and accrued expenses	3,939.0	4,184.5
Short term borrowings and capital leases	1,787.2	2,788.7
Intercompany payables	0.0	0.0
Short term intercompany loan payable	0.0	0.0
Other current liabilities	1,218.4	908.8
Total current liabilities	6,944.6	7,882.0
Long term borrowings and capital leases	16,733.7	16,752.4
Deferred tax liability	4,716.4	4,748.2
Long term intercompany loan payable	0.0	0.0
Other non-current liabilities	2,074.1	2,197.9
Total liabilities	30,468.8	31,580.5
Total equity	37,400.0	36,176.4
Total liabilities and equity	67,868.8	67,756.9
Eliminations
Current assets:
Cash and cash equivalents	0.0	0.0
Restricted cash	0.0	0.0
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.0	0.0
Intercompany receivables	(4,548.1)	(4,802.5)
Short term intercompany loan receivable	(974.0)	(2,006.3)
Total current assets	(5,522.1)	(6,808.8)
Investments	(96,985.6)	(94,947.2)
Property, plant and equipment (PP&E), net	0.0	0.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Deferred tax asset	(304.1)	(304.1)
Long term intercompany loan receivable	(13,440.0)	(13,659.5)
Other non-current assets	0.0	0.0
Total assets	(116,251.8)	(115,719.6)
Current liabilities:
Accounts payable and accrued expenses	0.0	0.0
Short term borrowings and capital leases	0.0	0.0
Intercompany payables	(4,548.1)	(4,802.5)
Short term intercompany loan payable	(974.0)	(2,006.3)
Other current liabilities	0.0	0.0
Total current liabilities	(5,522.1)	(6,808.8)
Long term borrowings and capital leases	0.0	0.0
Deferred tax liability	(304.1)	(304.1)
Long term intercompany loan payable	(13,440.0)	(13,659.5)
Other non-current liabilities	0.0	0.0
Total liabilities	(19,266.2)	(20,772.4)
Total equity	(96,985.6)	(94,947.2)
Total liabilities and equity	(116,251.8)	(115,719.6)
Shire plc (Parent Guarantor)
Current assets:
Cash and cash equivalents	0.0	0.0
Restricted cash	0.0	0.0
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.0	0.0
Intercompany receivables	0.0	0.0
Short term intercompany loan receivable	0.0	0.0
Total current assets	0.0	0.0
Investments	44,476.9	43,204.3
Property, plant and equipment (PP&E), net	0.0	0.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Deferred tax asset	0.0	0.0
Long term intercompany loan receivable	0.0	0.0
Other non-current assets	0.0	0.0
Total assets	44,476.9	43,204.3
Current liabilities:
Accounts payable and accrued expenses	1.0	0.2
Short term borrowings and capital leases	0.0	0.0
Intercompany payables	3,605.5	3,585.3
Short term intercompany loan payable	0.0	0.0
Other current liabilities	578.0	573.5
Total current liabilities	4,184.5	4,159.0
Long term borrowings and capital leases	0.0	0.0
Deferred tax liability	0.0	0.0
Long term intercompany loan payable	2,892.4	2,868.9
Other non-current liabilities	0.0	0.0
Total liabilities	7,076.9	7,027.9
Total equity	37,400.0	36,176.4
Total liabilities and equity	44,476.9	43,204.3
Baxalta Inc. (Baxalta Notes Subsidiary Issuer and SAIIDAC Notes Subsidiary Guarantor)
Current assets:
Cash and cash equivalents	0.0	0.5
Restricted cash	0.0	0.0
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	94.1	95.2
Intercompany receivables	0.0	0.0
Short term intercompany loan receivable	0.0	0.0
Total current assets	94.1	95.7
Investments	39,557.0	38,924.6
Property, plant and equipment (PP&E), net	5.6	7.6
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Deferred tax asset	304.1	304.1
Long term intercompany loan receivable	1,386.7	1,609.3
Other non-current assets	0.0	0.0
Total assets	41,347.5	40,941.3
Current liabilities:
Accounts payable and accrued expenses	67.0	18.1
Short term borrowings and capital leases	749.5	748.8
Intercompany payables	942.6	1,217.2
Short term intercompany loan payable	0.0	0.0
Other current liabilities	3.1	10.7
Total current liabilities	1,762.2	1,994.8
Long term borrowings and capital leases	4,292.4	4,308.9
Deferred tax liability	0.0	0.0
Long term intercompany loan payable	0.0	0.0
Other non-current liabilities	86.9	70.0
Total liabilities	6,141.5	6,373.7
Total equity	35,206.0	34,567.6
Total liabilities and equity	41,347.5	40,941.3
Non-Guarantor Non-Issuer Subsidiaries
Current assets:
Cash and cash equivalents	317.7	471.9
Restricted cash	35.5	39.4
Accounts receivable, net	3,140.5	3,009.8
Inventories	3,340.8	3,291.5
Prepaid expenses and other current assets	984.8	698.5
Intercompany receivables	4,510.5	4,682.3
Short term intercompany loan receivable	0.0	0.0
Total current assets	12,329.8	12,193.4
Investments	13,223.5	13,059.4
Property, plant and equipment (PP&E), net	6,454.5	6,627.8
Goodwill	19,988.6	19,831.7
Intangible assets, net	32,864.3	33,046.1
Deferred tax asset	189.2	188.8
Long term intercompany loan receivable	0.0	0.0
Other non-current assets	177.3	202.6
Total assets	85,227.2	85,149.8
Current liabilities:
Accounts payable and accrued expenses	3,863.5	4,080.3
Short term borrowings and capital leases	63.7	33.6
Intercompany payables	0.0	0.0
Short term intercompany loan payable	974.0	2,006.3
Other current liabilities	637.3	324.6
Total current liabilities	5,538.5	6,444.8
Long term borrowings and capital leases	388.0	393.3
Deferred tax liability	5,020.5	5,052.3
Long term intercompany loan payable	10,547.6	10,790.6
Other non-current liabilities	1,987.2	2,127.9
Total liabilities	23,481.8	24,808.9
Total equity	61,745.4	60,340.9
Total liabilities and equity	85,227.2	85,149.8
Non-Guarantor Subsidiaries of Baxalta Notes
Current assets:
Cash and cash equivalents	317.7	471.9
Restricted cash	35.5	39.4
Accounts receivable, net	3,140.5	3,009.8
Inventories	3,340.8	3,291.5
Prepaid expenses and other current assets	986.4	700.1
Intercompany receivables	4,548.1	4,802.5
Short term intercompany loan receivable	974.0	2,006.3
Total current assets	13,343.0	14,321.5
Investments	13,223.5	13,059.4
Property, plant and equipment (PP&E), net	6,454.5	6,627.8
Goodwill	19,988.6	19,831.7
Intangible assets, net	32,864.3	33,046.1
Deferred tax asset	189.2	188.8
Long term intercompany loan receivable	12,053.3	12,050.2
Other non-current assets	179.8	205.4
Total assets	98,296.2	99,330.9
Current liabilities:
Accounts payable and accrued expenses	3,871.0	4,166.2
Short term borrowings and capital leases	1,037.7	2,039.9
Intercompany payables	0.0	0.0
Short term intercompany loan payable	974.0	2,006.3
Other current liabilities	637.3	324.6
Total current liabilities	6,520.0	8,537.0
Long term borrowings and capital leases	12,441.3	12,443.5
Deferred tax liability	5,020.5	5,052.3
Long term intercompany loan payable	10,547.6	10,790.6
Other non-current liabilities	1,987.2	2,127.9
Total liabilities	36,516.6	38,951.3
Total equity	61,779.6	60,379.6
Total liabilities and equity	98,296.2	99,330.9
SAIIDAC (SAIIDAC Notes Subsidiary Issuer)
Current assets:
Cash and cash equivalents	0.0	0.0
Restricted cash	0.0	0.0
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	1.6	1.6
Intercompany receivables	37.6	120.2
Short term intercompany loan receivable	974.0	2,006.3
Total current assets	1,013.2	2,128.1
Investments	0.0	0.0
Property, plant and equipment (PP&E), net	0.0	0.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Deferred tax asset	0.0	0.0
Long term intercompany loan receivable	12,053.3	12,050.2
Other non-current assets	2.5	2.8
Total assets	13,069.0	14,181.1
Current liabilities:
Accounts payable and accrued expenses	7.5	85.9
Short term borrowings and capital leases	974.0	2,006.3
Intercompany payables	0.0	0.0
Short term intercompany loan payable	0.0	0.0
Other current liabilities	0.0	0.0
Total current liabilities	981.5	2,092.2
Long term borrowings and capital leases	12,053.3	12,050.2
Deferred tax liability	0.0	0.0
Long term intercompany loan payable	0.0	0.0
Other non-current liabilities	0.0	0.0
Total liabilities	13,034.8	14,142.4
Total equity	34.2	38.7
Total liabilities and equity	$ 13,069.0	$ 14,181.1