Revenue Recognition - Product revenue allowance and reserve categories (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	$ 1,507	$ 1,243
Provision related to current period sales	1,306	132
Credit or payments made during the period	(1,913)	(33)
Balance at the end	900	1,342
Chargebacks, discounts and fees
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	177	813
Provision related to current period sales	736	82
Credit or payments made during the period	(756)	(9)
Balance at the end	157	886
Government and other rebates
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	1,312	422
Provision related to current period sales	562	50
Credit or payments made during the period	(1,157)	(24)
Balance at the end	717	448
Returns
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	18	8
Provision related to current period sales	8
Balance at the end	$ 26	$ 8