Convertible Bonds (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Debt Instrument [Line Items]
Debt issuance date	May 09, 2007
Issuance price to principal amount, percent	100.00%
Final maturity date	May 09, 2014
Repayment terms	The Bonds may be redeemed at the option of the Company, at their principal amount together with accrued and unpaid interest if: (i) at any time after May 23, 2012 if on no less than 20 dealing days in any period of 30 consecutive dealing days the value of Shire’s ordinary shares underlying each Bond in the principal amount of $100,000 would exceed $130,000; or (ii) at any time conversion rights have been exercised, and/or purchases and corresponding cancellations, and/or redemptions effected in respect of 85% or more in principal amount of Bonds originally issued The Bonds are repayable in US dollars, but also contain provisions entitling the Company to settle redemption amounts in Pounds sterling or in the case of Final Maturity Date by delivery of the underlying ordinary shares and, if necessary, a cash top-up amount. As the Bonds will be redeemed within twelve months of the balance sheet date, the Bonds have been presented as a current liability at September 30, 2013
Stated interest rate	2.75%
Principal amount	$ 1,100