Guarantor Financial Information (Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 193.2	$ 472.4	$ 209.3
Restricted cash	39.9	39.4	34.3
Accounts receivable, net	3,207.4	3,009.8
Inventories	3,458.7	3,291.5
Other current assets	900.1	795.3
Intercompany receivables	0.0	0.0
Short term intercompany loan receivable	0.0	0.0
Total current assets	7,799.3	7,608.4
Non-current assets:
Investments	470.7	241.1
Property, plant and equipment (PP&E), net	6,453.0	6,635.4
Goodwill	19,095.0	19,831.7	19,718.4	$ 17,888.2
Intangible assets, net	29,625.4	33,046.1	$ 33,350.3	$ 34,697.5
Deferred tax asset	151.2	188.8
Long term intercompany loan receivable	0.0	0.0
Other non-current assets	171.3	205.4
Total assets	63,765.9	67,756.9
Current liabilities:
Accounts payable and accrued expenses	4,025.1	4,184.5
Short term borrowings and capital leases	4,248.7	2,788.7
Intercompany payables	0.0	0.0
Short term intercompany loan payable	0.0	0.0
Other current liabilities	237.8	908.8
Total current liabilities	8,511.6	7,882.0
Long term borrowings and capital leases	11,098.0	16,752.4
Deferred tax liability	4,571.2	4,748.2
Long term intercompany loan payable	0.0	0.0
Other non-current liabilities	2,294.9	2,197.9
Total liabilities	26,475.7	31,580.5
Total equity	37,290.2	36,176.4
Total liabilities and equity	63,765.9	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
Other current assets	0.0	0.0
Intercompany receivables	(7,852.8)	(4,802.5)
Short term intercompany loan receivable	(4,210.3)	(2,006.3)
Total current assets	(12,063.1)	(6,808.8)
Non-current assets:
Investments	(96,085.0)	(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	(12,270.6)	(13,659.5)
Other non-current assets	0.0	0.0
Total assets	(120,722.8)	(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	(7,852.8)	(4,802.5)
Short term intercompany loan payable	(4,210.3)	(2,006.3)
Other current liabilities	0.0	0.0
Total current liabilities	(12,063.1)	(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	(12,270.6)	(13,659.5)
Other non-current liabilities	0.0	0.0
Total liabilities	(24,637.8)	(20,772.4)
Total equity	(96,085.0)	(94,947.2)
Total liabilities and equity	(120,722.8)	(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
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
Non-current assets:
Investments	44,695.6	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	44,695.6	43,204.3
Current liabilities:
Accounts payable and accrued expenses	6.4	0.2
Short term borrowings and capital leases	0.0	0.0
Intercompany payables	3,612.5	3,585.3
Short term intercompany loan payable	0.0	0.0
Other current liabilities	0.0	573.5
Total current liabilities	3,618.9	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	3,786.5	2,868.9
Other non-current liabilities	0.0	0.0
Total liabilities	7,405.4	7,027.9
Total equity	37,290.2	36,176.4
Total liabilities and equity	44,695.6	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
Other current assets	81.2	95.2
Intercompany receivables	0.0	0.0
Short term intercompany loan receivable	0.0	0.0
Total current assets	81.2	95.7
Non-current assets:
Investments	38,547.8	38,924.6
Property, plant and equipment (PP&E), net	4.6	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	3,507.0	1,609.3
Other non-current assets	0.0	0.0
Total assets	42,444.7	40,941.3
Current liabilities:
Accounts payable and accrued expenses	33.6	18.1
Short term borrowings and capital leases	0.0	748.8
Intercompany payables	4,240.3	1,217.2
Short term intercompany loan payable	0.0	0.0
Other current liabilities	3.8	10.7
Total current liabilities	4,277.7	1,994.8
Long term borrowings and capital leases	1,939.9	4,308.9
Deferred tax liability	0.0	0.0
Long term intercompany loan payable	0.0	0.0
Other non-current liabilities	60.3	70.0
Total liabilities	6,277.9	6,373.7
Total equity	36,166.8	34,567.6
Total liabilities and equity	42,444.7	40,941.3
Non-Guarantor Non-Issuer Subsidiaries
Current assets:
Cash and cash equivalents	193.2	471.9
Restricted cash	39.9	39.4
Accounts receivable, net	3,207.4	3,009.8
Inventories	3,458.7	3,291.5
Other current assets	817.4	698.5
Intercompany receivables	7,811.8	4,682.3
Short term intercompany loan receivable	0.0	0.0
Total current assets	15,528.4	12,193.4
Non-current assets:
Investments	13,312.3	13,059.4
Property, plant and equipment (PP&E), net	6,448.4	6,627.8
Goodwill	19,095.0	19,831.7
Intangible assets, net	29,625.4	33,046.1
Deferred tax asset	151.2	188.8
Long term intercompany loan receivable	0.0	0.0
Other non-current assets	169.4	202.6
Total assets	84,330.1	85,149.8
Current liabilities:
Accounts payable and accrued expenses	3,977.1	4,080.3
Short term borrowings and capital leases	38.4	33.6
Intercompany payables	0.0	0.0
Short term intercompany loan payable	4,210.3	2,006.3
Other current liabilities	234.0	324.6
Total current liabilities	8,459.8	6,444.8
Long term borrowings and capital leases	394.5	393.3
Deferred tax liability	4,875.3	5,052.3
Long term intercompany loan payable	8,484.1	10,790.6
Other non-current liabilities	2,234.6	2,127.9
Total liabilities	24,448.3	24,808.9
Total equity	59,881.8	60,340.9
Total liabilities and equity	84,330.1	85,149.8
Non-Guarantor Subsidiaries of Baxalta Notes
Current assets:
Cash and cash equivalents	193.2	471.9
Restricted cash	39.9	39.4
Accounts receivable, net	3,207.4	3,009.8
Inventories	3,458.7	3,291.5
Other current assets	818.9	700.1
Intercompany receivables	7,852.8	4,802.5
Short term intercompany loan receivable	4,210.3	2,006.3
Total current assets	19,781.2	14,321.5
Non-current assets:
Investments	13,312.3	13,059.4
Property, plant and equipment (PP&E), net	6,448.4	6,627.8
Goodwill	19,095.0	19,831.7
Intangible assets, net	29,625.4	33,046.1
Deferred tax asset	151.2	188.8
Long term intercompany loan receivable	8,763.6	12,050.2
Other non-current assets	171.3	205.4
Total assets	97,348.4	99,330.9
Current liabilities:
Accounts payable and accrued expenses	3,985.1	4,166.2
Short term borrowings and capital leases	4,248.7	2,039.9
Intercompany payables	0.0	0.0
Short term intercompany loan payable	4,210.3	2,006.3
Other current liabilities	234.0	324.6
Total current liabilities	12,678.1	8,537.0
Long term borrowings and capital leases	9,158.1	12,443.5
Deferred tax liability	4,875.3	5,052.3
Long term intercompany loan payable	8,484.1	10,790.6
Other non-current liabilities	2,234.6	2,127.9
Total liabilities	37,430.2	38,951.3
Total equity	59,918.2	60,379.6
Total liabilities and equity	97,348.4	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
Other current assets	1.5	1.6
Intercompany receivables	41.0	120.2
Short term intercompany loan receivable	4,210.3	2,006.3
Total current assets	4,252.8	2,128.1
Non-current assets:
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	8,763.6	12,050.2
Other non-current assets	1.9	2.8
Total assets	13,018.3	14,181.1
Current liabilities:
Accounts payable and accrued expenses	8.0	85.9
Short term borrowings and capital leases	4,210.3	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	4,218.3	2,092.2
Long term borrowings and capital leases	8,763.6	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	12,981.9	14,142.4
Total equity	36.4	38.7
Total liabilities and equity	$ 13,018.3	$ 14,181.1