Accounts Payable and Accrued Expenses (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Accounts Payable and Accrued Expenses
Accounts payable	$ 6,708	$ 10,203
Accrued expenses:
Royalties and rebates	48,213	37,264
Payroll related	26,930	26,013
Research related	5,780	5,057
Other	4,613	4,651
Total accrued expenses	85,536	72,985
Total accounts payable and accrued expenses	$ 92,244	$ 83,188