The following tables summarize activity in each of the net product revenue allowance and reserve categories described above for the six months ended June 30, 2018 and 2017:

In thousands	Trade Allowances			Rebates, Chargebacks and Discounts			Product Returns			Other Incentives			Total
Balance as of December 31, 2017	$	12,035		$	32,064		$	1,887		$	2,107		$	48,093
Provision related to current period sales		19,077			78,051			491			9,234			106,853
Provision related to prior period sales		(400	)		(836	)		—			(69	)		(1,305	)
Credits/payments made for current period sales		(9,097	)		(40,547	)		—			(6,533	)		(56,177	)
Credits/payments made for prior period sales		(5,282	)		(27,028	)		(40	)		(2,297	)		(34,647	)
Balance as of June 30, 2018	$	16,333		$	41,704		$	2,338		$	2,442		$	62,817

In thousands	Trade Allowances			Rebates, Chargebacks and Discounts			Product Returns			Other Incentives			Total
Balance as of December 31, 2016	$	3,743		$	20,915		$	859		$	1,681		$	27,198
Provision related to current period sales		15,685			53,078			1,259			6,768			76,790
Provision related to prior period sales		(298	)		(841	)		—			(82	)		(1,221	)
Credits/payments made for current period sales		(5,496	)		(34,771	)		(21	)		(4,922	)		(45,210	)
Credits/payments made for prior period sales		(3,107	)		(16,722	)		(24	)		(1,770	)		(21,623	)
Balance as of June 30, 2017	$	10,527		$	21,659		$	2,073		$	1,675		$	35,934