Guarantor Financial Information (Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash (used in)/provided by operating activities	$ 1,681.9	$ 980.4
CASH FLOWS FROM INVESTING ACTIVITIES:
Transactions with subsidiaries	0.0	0.0
Movements in restricted cash	(8.6)	67.2
Purchases of businesses, net of cash acquired	0.0	(17,476.2)
Purchases of PP&E and non-current investments	(391.1)	(179.1)
(Payment)/proceeds from sale of investments	40.6
Other, net	3.2	3.3
Net cash used in investing activities	(355.9)	(17,584.8)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit, long term and short term borrowings	2,111.9	18,895.0
Repayment of revolving line of credit, long term and short term borrowings	(3,527.9)	(1,500.3)
Proceeds from/to intercompany borrowings	0.0	0.0
Payment of dividend	(234.7)	(130.2)
Debt issuance costs		(112.3)
Proceeds from exercise of options	79.5	0.1
Other, net	(24.0)	11.9
Net cash (used in)/provided by financing activities	(1,595.2)	17,164.2
Effect of foreign exchange rate changes on cash and cash equivalents	4.1	(1.9)
Net (decrease)/increase in cash and cash equivalents	(265.1)	557.9
Cash and cash equivalents at beginning of period	528.8	135.5
Cash and cash equivalents at end of period	263.7	693.4
Eliminations
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash (used in)/provided by operating activities	0.0	0.0
CASH FLOWS FROM INVESTING ACTIVITIES:
Transactions with subsidiaries	3,032.1	22,398.6
Movements in restricted cash	0.0	0.0
Purchases of businesses, net of cash acquired		0.0
Purchases of PP&E and non-current investments	0.0	0.0
(Payment)/proceeds from sale of investments	0.0
Other, net	0.0	0.0
Net cash used in investing activities	3,032.1	22,398.6
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit, long term and short term borrowings	0.0	0.0
Repayment of revolving line of credit, long term and short term borrowings	0.0	0.0
Proceeds from/to intercompany borrowings	(3,032.1)	(22,398.6)
Payment of dividend	0.0	0.0
Debt issuance costs		0.0
Proceeds from exercise of options	0.0	0.0
Other, net	0.0	0.0
Net cash (used in)/provided by financing activities	(3,032.1)	(22,398.6)
Effect of foreign exchange rate changes on cash and cash equivalents	0.0	0.0
Net (decrease)/increase in cash and cash equivalents	0.0	0.0
Cash and cash equivalents at beginning of period	0.0	0.0
Cash and cash equivalents at end of period	0.0	0.0
Shire plc (Parent Guarantor)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash (used in)/provided by operating activities	(36.0)	(13.8)
CASH FLOWS FROM INVESTING ACTIVITIES:
Transactions with subsidiaries	(760.6)	(1,900.0)
Movements in restricted cash	0.0	0.0
Purchases of businesses, net of cash acquired		0.0
Purchases of PP&E and non-current investments	0.0	0.0
(Payment)/proceeds from sale of investments	0.0
Other, net	0.0	0.0
Net cash used in investing activities	(760.6)	(1,900.0)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit, long term and short term borrowings	2,110.0	905.0
Repayment of revolving line of credit, long term and short term borrowings	(1,825.0)	(1,500.0)
Proceeds from/to intercompany borrowings	539.0	2,523.2
Payment of dividend	(27.6)	(14.4)
Debt issuance costs		0.0
Proceeds from exercise of options	0.2	0.0
Other, net	0.0	0.0
Net cash (used in)/provided by financing activities	796.6	1,913.8
Effect of foreign exchange rate changes on cash and cash equivalents	0.0	0.0
Net (decrease)/increase in cash and cash equivalents	0.0	0.0
Cash and cash equivalents at beginning of period	0.0	0.0
Cash and cash equivalents at end of period	0.0	0.0
SAIIDAC (SAIIDAC Notes Subsidiary Issuer)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash (used in)/provided by operating activities	4.5	63.5
CASH FLOWS FROM INVESTING ACTIVITIES:
Transactions with subsidiaries	0.0	(17,922.0)
Movements in restricted cash	0.0	0.0
Purchases of businesses, net of cash acquired		0.0
Purchases of PP&E and non-current investments	0.0	0.0
(Payment)/proceeds from sale of investments	0.0
Other, net	0.0	0.0
Net cash used in investing activities	0.0	(17,922.0)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit, long term and short term borrowings	0.0	17,990.0
Repayment of revolving line of credit, long term and short term borrowings	(1,700.0)	0.0
Proceeds from/to intercompany borrowings	1,695.5	0.0
Payment of dividend	0.0	0.0
Debt issuance costs		(131.5)
Proceeds from exercise of options	0.0	0.0
Other, net	0.0	0.0
Net cash (used in)/provided by financing activities	(4.5)	17,858.5
Effect of foreign exchange rate changes on cash and cash equivalents	0.0	0.0
Net (decrease)/increase in cash and cash equivalents	0.0	0.0
Cash and cash equivalents at beginning of period	0.0	0.0
Cash and cash equivalents at end of period	0.0	0.0
Baxalta Inc. (Baxalta Notes Subsidiary Issuer and SAIIDAC Notes Subsidiary Guarantor)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash (used in)/provided by operating activities	(1.8)	1.6
CASH FLOWS FROM INVESTING ACTIVITIES:
Transactions with subsidiaries	(343.5)	0.0
Movements in restricted cash	0.0	0.0
Purchases of businesses, net of cash acquired		0.0
Purchases of PP&E and non-current investments	0.0	(1.9)
(Payment)/proceeds from sale of investments	(4.0)
Other, net	2.0	0.0
Net cash used in investing activities	(345.5)	(1.9)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit, long term and short term borrowings	0.0	0.0
Repayment of revolving line of credit, long term and short term borrowings	0.0	0.0
Proceeds from/to intercompany borrowings	303.7	53.4
Payment of dividend	0.0	0.0
Debt issuance costs		0.0
Proceeds from exercise of options	4.6	0.1
Other, net	(0.8)	0.2
Net cash (used in)/provided by financing activities	307.5	53.7
Effect of foreign exchange rate changes on cash and cash equivalents	0.0	0.0
Net (decrease)/increase in cash and cash equivalents	(39.8)	53.4
Cash and cash equivalents at beginning of period	41.7	0.0
Cash and cash equivalents at end of period	1.9	53.4
Non-Guarantor Non-Issuer Subsidiaries
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash (used in)/provided by operating activities	1,715.2	929.1
CASH FLOWS FROM INVESTING ACTIVITIES:
Transactions with subsidiaries	(1,928.0)	(2,576.6)
Movements in restricted cash	(8.6)	67.2
Purchases of businesses, net of cash acquired		(17,476.2)
Purchases of PP&E and non-current investments	(391.1)	(177.2)
(Payment)/proceeds from sale of investments	44.6
Other, net	1.2	3.3
Net cash used in investing activities	(2,281.9)	(20,159.5)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit, long term and short term borrowings	1.9	0.0
Repayment of revolving line of credit, long term and short term borrowings	(2.9)	(0.3)
Proceeds from/to intercompany borrowings	493.9	19,822.0
Payment of dividend	(207.1)	(115.8)
Debt issuance costs		19.2
Proceeds from exercise of options	74.7	0.0
Other, net	(23.2)	11.7
Net cash (used in)/provided by financing activities	337.3	19,736.8
Effect of foreign exchange rate changes on cash and cash equivalents	4.1	(1.9)
Net (decrease)/increase in cash and cash equivalents	(225.3)	504.5
Cash and cash equivalents at beginning of period	487.1	135.5
Cash and cash equivalents at end of period	261.8	640.0
Non-Guarantor Subsidiaries of Baxalta Notes
CASH FLOWS FROM OPERATING ACTIVITIES:
Net cash (used in)/provided by operating activities	1,719.7	992.6
CASH FLOWS FROM INVESTING ACTIVITIES:
Transactions with subsidiaries	(1,928.0)	(20,498.6)
Movements in restricted cash	(8.6)	67.2
Purchases of businesses, net of cash acquired		(17,476.2)
Purchases of PP&E and non-current investments	(391.1)	(177.2)
(Payment)/proceeds from sale of investments	44.6
Other, net	1.2	3.3
Net cash used in investing activities	(2,281.9)	(38,081.5)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from revolving line of credit, long term and short term borrowings	1.9	17,990.0
Repayment of revolving line of credit, long term and short term borrowings	(1,702.9)	(0.3)
Proceeds from/to intercompany borrowings	2,189.4	19,822.0
Payment of dividend	(207.1)	(115.8)
Debt issuance costs		(112.3)
Proceeds from exercise of options	74.7	0.0
Other, net	(23.2)	11.7
Net cash (used in)/provided by financing activities	332.8	37,595.3
Effect of foreign exchange rate changes on cash and cash equivalents	4.1	(1.9)
Net (decrease)/increase in cash and cash equivalents	(225.3)	504.5
Cash and cash equivalents at beginning of period	487.1	135.5
Cash and cash equivalents at end of period	$ 261.8	$ 640.0