Debt	9 Months Ended
Sep. 30, 2017
Debt [Abstract]
Debt	Debt On June 22, 2015, Alexion entered into a credit agreement (Credit Agreement) with a syndicate of banks, which provides for a $3,500 term loan facility and a $500 revolving credit facility maturing in five years. Borrowings under the term loan are payable in quarterly installments equal to 1.25% of the original loan amount, beginning December 31, 2015. Final repayment of the term loan and revolving credit loans are due on June 22, 2020. In addition to borrowings in which prior notice is required, the revolving credit facility includes a sublimit of $100 in the form of letters of credit and borrowings on same-day notice, referred to as swingline loans, of up to $25. Borrowings can be used for working capital requirements, acquisitions and other general corporate purposes. With the consent of the lenders and the administrative agent, and subject to satisfaction of certain conditions, we may increase the term loan facility and/or the revolving credit facility in an amount that does not cause our consolidated net leverage ratio to exceed the maximum allowable amount. In connection with entering into the Credit Agreement, we paid $45 in financing costs which are being amortized as interest expense over the life of the debt. Amortization expense associated with deferred financing costs for each of the three and nine months ended September 30, 2017 and 2016 was $2 and $7, respectively. We made principal payments of $131 during the nine months ended September 30, 2017. As of September 30, 2017, $2,950 remained outstanding on the term loan. As of September 30, 2017, we had open letters of credit of $4, and our borrowing availability under the revolving facility was $496. The fair value of our long term debt, which is measured using Level 2 inputs, approximates book value.

Debt

On June 22, 2015, Alexion entered into a credit agreement (Credit Agreement) with a syndicate of banks, which provides for a $3,500 term loan facility and a $500 revolving credit facility maturing in five years. Borrowings under the term loan are payable in quarterly installments equal to 1.25% of the original loan amount, beginning December 31, 2015. Final repayment of the term loan and revolving credit loans are due on June 22, 2020. In addition to borrowings in which prior notice is required, the revolving credit facility includes a sublimit of $100 in the form of letters of credit and borrowings on same-day notice, referred to as swingline loans, of up to $25. Borrowings can be used for working capital requirements, acquisitions and other general corporate purposes. With the consent of the lenders and the administrative agent, and subject to satisfaction of certain conditions, we may increase the term loan facility and/or the revolving credit facility in an amount that does not cause our consolidated net leverage ratio to exceed the maximum allowable amount.

In connection with entering into the Credit Agreement, we paid $45 in financing costs which are being amortized as interest expense over the life of the debt. Amortization expense associated with deferred financing costs for each of the three and nine months ended September 30, 2017 and 2016 was $2 and $7, respectively.

We made principal payments of $131 during the nine months ended September 30, 2017. As of September 30, 2017, $2,950 remained outstanding on the term loan. As of September 30, 2017, we had open letters of credit of $4, and our borrowing availability under the revolving facility was $496.

The fair value of our long term debt, which is measured using Level 2 inputs, approximates book value.