Accrued Expenses (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accrued Expenses
Royalties and rebates	$ 37,264	$ 33,002
Payroll related	26,013	16,945
Research related	5,057	2,939
Other	4,651	4,341
Total	$ 72,985	$ 57,227