Related-party arrangements	12 Months Ended
Dec. 31, 2015
Related-party arrangements	7. Related-party arrangements In October 2007, the Company entered into a $350.0 million loan arrangement with its principal stockholder. The Loan Arrangement has been amended from time to time. On October 31, 2013, the promissory note underlying The Mann Group Loan Arrangement was amended to, among other things, extend the maturity date of the loan to January 5, 2020, extend the date through which the Company can borrow under The Mann Group Loan Arrangement to December 31, 2019, increase the aggregate borrowing amount under The Mann Group Loan Arrangement from $350.0 million to $370.0 million and provide that repayments or cancellations of principal under The Mann Group Loan Arrangement will not be available for reborrowing. As of December 31, 2015, the total principal amount outstanding under The Mann Group Loan Arrangement was $49.5 million, and the amount available for future borrowings was $30.1 million. Interest, at a fixed rate of 5.84%, is due and payable quarterly in arrears on the first day of each calendar quarter for the preceding quarter, or at such other time as the Company and The Mann Group mutually agree. All or any portion of accrued and unpaid interest that becomes due and payable may be paid-in-kind and capitalized as additional borrowings at any time upon mutual agreement of the parties, and has been classified as non-current. The Mann Group can require the Company to prepay up to $200.0 million in advances that have been outstanding for at least 12 months (less approximately $105.0 million aggregate principal amount that has been cancelled in connection with two common stock purchase agreements). If The Mann Group exercises this right, the Company will have 90 days after The Mann Group provides written notice (or the number of days to maturity of the note if less than 90 days) to prepay such advances. However, pursuant to a letter agreement entered into in August 2010, The Mann Group has agreed to not require the Company to prepay amounts outstanding under the amended and restated promissory note if the prepayment would require the Company to use its working capital resources. In addition, The Mann Group entered into a subordination agreement with Deerfield pursuant to which The Mann Group agreed with Deerfield not to demand or accept any payment under The Mann Group Loan Arrangement until the Company’s payment obligations to Deerfield under the Facility Agreement have been satisfied in full. Subject to the foregoing, in the event of a default under The Mann Group Loan Arrangement, all unpaid principal and interest either becomes immediately due and payable or may be accelerated at The Mann Group’s option, and the interest rate will increase to the one-year LIBOR rate calculated on the date of the initial advance or in effect on the date of default, whichever is greater, plus 5% per annum. All borrowings under The Mann Group Loan Arrangement are unsecured. The Mann Group Loan Arrangement contains no financial covenants. As of December 31, 2015 and 2014, the Company had accrued and unpaid interest of $6.4 million and $3.5 million, in long term other liabilities respectively, which related to the amount outstanding and had $30.1 million of available borrowings. Interest expense on the Company’s note payable to the Company’s principal stockholder for the years ended December 31, 2015, 2014, and 2013 was $2.9 million, $2.9 million, and $6.3 million, respectively. In May 2015, the Company entered into sublease agreement with the Alfred Mann Foundation for Scientific Research (the “Mann Foundation”), a California Not-For-Profit Corporation. The lease is for approximately 12,500 square feet of office space in Valencia, California and expires in April 2017. The office space contains the Company’s principal executive offices. Lease payments to the Mann Foundation for the year ended December 31, 2015 were $175,000. There were no lease payments to the Mann Foundation for the years ended December 31, 2014 and 2013. In connection with certain meetings of the Company’s board of directors and on other occasions when the Company’s business necessitated air travel for the Company’s principal stockholder and other Company employees, the Company utilized the principal stockholder’s private aircraft, and the Company paid the charter company that manages the aircraft on behalf of the Company’s principal stockholder approximately $18,000, $79,000, and $82,000, respectively, for the years ended December 31, 2015, 2014, and 2013 on the basis of the corresponding cost of commercial airfare. The Company has entered into indemnification agreements with each of its directors and executive officers, in addition to the indemnification provided for in its amended and restated certificate of incorporation and amended and restated bylaws (see Note 14 — Commitments and contingencies).

7. Related-party arrangements

In October 2007, the Company entered into a $350.0 million loan arrangement with its principal stockholder. The Loan Arrangement has been amended from time to time. On October 31, 2013, the promissory note underlying The Mann Group Loan Arrangement was amended to, among other things, extend the maturity date of the loan to January 5, 2020, extend the date through which the Company can borrow under The Mann Group Loan Arrangement to December 31, 2019, increase the aggregate borrowing amount under The Mann Group Loan Arrangement from $350.0 million to $370.0 million and provide that repayments or cancellations of principal under The Mann Group Loan Arrangement will not be available for reborrowing.

As of December 31, 2015, the total principal amount outstanding under The Mann Group Loan Arrangement was $49.5 million, and the amount available for future borrowings was $30.1 million. Interest, at a fixed rate of 5.84%, is due and payable quarterly in arrears on the first day of each calendar quarter for the preceding quarter, or at such other time as the Company and The Mann Group mutually agree. All or any portion of accrued and unpaid interest that becomes due and payable may be paid-in-kind and capitalized as additional borrowings at any time upon mutual agreement of the parties, and has been classified as non-current. The Mann Group can require the Company to prepay up to $200.0 million in advances that have been outstanding for at least 12 months (less approximately $105.0 million aggregate principal amount that has been cancelled in connection with two common stock purchase agreements). If The Mann Group exercises this right, the Company will have 90 days after The Mann Group provides written notice (or the number of days to maturity of the note if less than 90 days) to prepay such advances. However, pursuant to a letter agreement entered into in August 2010, The Mann Group has agreed to not require the Company to prepay amounts outstanding under the amended and restated promissory note if the prepayment would require the Company to use its working capital resources. In addition, The Mann Group entered into a subordination agreement with Deerfield pursuant to which The Mann Group agreed with Deerfield not to demand or accept any payment under The Mann Group Loan Arrangement until the Company’s payment obligations to Deerfield under the Facility Agreement have been satisfied in full. Subject to the foregoing, in the event of a default under The Mann Group Loan Arrangement, all unpaid principal and interest either becomes immediately due and payable or may be accelerated at The Mann Group’s option, and the interest rate will increase to the one-year LIBOR rate calculated on the date of the initial advance or in effect on the date of default, whichever is greater, plus 5% per annum. All borrowings under The Mann Group Loan Arrangement are unsecured. The Mann Group Loan Arrangement contains no financial covenants.

As of December 31, 2015 and 2014, the Company had accrued and unpaid interest of $6.4 million and $3.5 million, in long term other liabilities respectively, which related to the amount outstanding and had $30.1 million of available borrowings. Interest expense on the Company’s note payable to the Company’s principal stockholder for the years ended December 31, 2015, 2014, and 2013 was $2.9 million, $2.9 million, and $6.3 million, respectively.

In May 2015, the Company entered into sublease agreement with the Alfred Mann Foundation for Scientific Research (the “Mann Foundation”), a California Not-For-Profit Corporation. The lease is for approximately 12,500 square feet of office space in Valencia, California and expires in April 2017. The office space contains the Company’s principal executive offices. Lease payments to the Mann Foundation for the year ended December 31, 2015 were $175,000. There were no lease payments to the Mann Foundation for the years ended December 31, 2014 and 2013.

In connection with certain meetings of the Company’s board of directors and on other occasions when the Company’s business necessitated air travel for the Company’s principal stockholder and other Company employees, the Company utilized the principal stockholder’s private aircraft, and the Company paid the charter company that manages the aircraft on behalf of the Company’s principal stockholder approximately $18,000, $79,000, and $82,000, respectively, for the years ended December 31, 2015, 2014, and 2013 on the basis of the corresponding cost of commercial airfare.

The Company has entered into indemnification agreements with each of its directors and executive officers, in addition to the indemnification provided for in its amended and restated certificate of incorporation and amended and restated bylaws (see Note 14 — Commitments and contingencies).