Accrued Expenses and Other Current Liabilities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Accrued Expenses and Other Current Liabilities
Other accrued expenses	$ 10,447	$ 9,351
Write-down of excess non-cancelable ZURAMPIC sample purchase commitments	1,353
Lesinurad transaction
Accrued Expenses and Other Current Liabilities
Other accrued expenses	600	$ 2,800
Write-down of excess non-cancelable ZURAMPIC sample purchase commitments	$ 1,300