Liability Related to Sale of Future Royalties	6 Months Ended
Jun. 30, 2018
Liability Related To Sale Of Potential Future Royalties [Abstract]
Liability Related to Sale of Future Royalties	Note 4 — Liability Related to Sale of Future Royalties On February 24, 2012, we entered into a Purchase and Sale Agreement (the Purchase and Sale Agreement) with RPI Finance Trust (RPI), an affiliate of Royalty Pharma, pursuant to which we sold, and RPI purchased, our right to receive royalty payments (the Royalty Entitlement) arising from the worldwide net sales, from and after January 1, 2012, of (a) CIMZIA^®, under our license, manufacturing and supply agreement with UCB Pharma (UCB), and (b) MIRCERA^®, under our license, manufacturing and supply agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (together referred to as Roche). We received aggregate cash proceeds of $124.0 million for the Royalty Entitlement. As part of this sale, we incurred approximately $4.4 million in transaction costs, which will be amortized to interest expense over the estimated life of the Purchase and Sale Agreement. Although we sold all of our rights to receive royalties from the CIMZIA^®and MIRCERA^® products, as a result of our ongoing manufacturing and supply obligations related to the generation of these royalties, we will continue to account for these royalties as revenue. We recorded the $124.0 million in proceeds from this transaction as a liability (Royalty Obligation) that will be amortized using the interest method over the estimated life of the Purchase and Sale Agreement as royalties from the CIMZIA^® and MIRCERA^® products are remitted directly to RPI. During the six months ended June 30, 2018 and 2017, we recognized $16.0 million and $13.3 million, respectively, in non-cash royalty revenue from net sales of CIMZIA^® and MIRCERA^®, and we recorded $10.0 million and $9.1 million, respectively, of related non-cash interest expense. We periodically assess the estimated royalty payments to RPI from UCB and Roche and to the extent such payments are greater or less than our initial estimates or the timing of such payments is materially different from our original estimates, we will prospectively adjust the amortization of the Royalty Obligation. From inception through 2017, our estimate of the total interest expense on the Royalty Obligation resulted in an effective annual interest rate of approximately 17%. During the three months ended December 31, 2017, as a result of increases in the forecasted sales of CIMZIA^®, our estimate of the effective annual interest rate over the life of the agreement increased to 17.6%, which results in a prospective interest rate of approximately 21%. The Purchase and Sale Agreement grants RPI the right to receive certain reports and other information relating to the Royalty Entitlement and contains other representations and warranties, covenants and indemnification obligations that are customary for a transaction of this nature. To our knowledge, we are currently in compliance with these provisions of the Purchase and Sale Agreement; however, if we were to breach our obligations, we could be required to pay damages to RPI that are not limited to the purchase price we received in the sale transaction.

Note 4 — Liability Related to Sale of Future Royalties

On February 24, 2012, we entered into a Purchase and Sale Agreement (the Purchase and Sale Agreement) with RPI Finance Trust (RPI), an affiliate of Royalty Pharma, pursuant to which we sold, and RPI purchased, our right to receive royalty payments (the Royalty Entitlement) arising from the worldwide net sales, from and after January 1, 2012, of (a) CIMZIA^®, under our license, manufacturing and supply agreement with UCB Pharma (UCB), and (b) MIRCERA^®, under our license, manufacturing and supply agreement with F. Hoffmann-La Roche Ltd and Hoffmann-La Roche Inc. (together referred to as Roche). We received aggregate cash proceeds of $124.0 million for the Royalty Entitlement. As part of this sale, we incurred approximately $4.4 million in transaction costs, which will be amortized to interest expense over the estimated life of the Purchase and Sale Agreement. Although we sold all of our rights to receive royalties from the CIMZIA^®and MIRCERA^® products, as a result of our ongoing manufacturing and supply obligations related to the generation of these royalties, we will continue to account for these royalties as revenue. We recorded the $124.0 million in proceeds from this transaction as a liability (Royalty Obligation) that will be amortized using the interest method over the estimated life of the Purchase and Sale Agreement as royalties from the CIMZIA^® and MIRCERA^® products are remitted directly to RPI. During the six months ended June 30, 2018 and 2017, we recognized $16.0 million and $13.3 million, respectively, in non-cash royalty revenue from net sales of CIMZIA^® and MIRCERA^®, and we recorded $10.0 million and $9.1 million, respectively, of related non-cash interest expense.

We periodically assess the estimated royalty payments to RPI from UCB and Roche and to the extent such payments are greater or less than our initial estimates or the timing of such payments is materially different from our original estimates, we will prospectively adjust the amortization of the Royalty Obligation. From inception through 2017, our estimate of the total interest expense on the Royalty Obligation resulted in an effective annual interest rate of approximately 17%. During the three months ended December 31, 2017, as a result of increases in the forecasted sales of CIMZIA^®, our estimate of the effective annual interest rate over the life of the agreement increased to 17.6%, which results in a prospective interest rate of approximately 21%.

The Purchase and Sale Agreement grants RPI the right to receive certain reports and other information relating to the Royalty Entitlement and contains other representations and warranties, covenants and indemnification obligations that are customary for a transaction of this nature. To our knowledge, we are currently in compliance with these provisions of the Purchase and Sale Agreement; however, if we were to breach our obligations, we could be required to pay damages to RPI that are not limited to the purchase price we received in the sale transaction.