Product Revenue - Schedule of Product Revenue Allowance and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Contractual Adjustments
Contractual adjustments, beginning balance	$ 253	$ 156
Contractual adjustments, current provisions relating to sales in the current year	1,422	1,300
Contractual adjustments, adjustments relating to prior years	(51)	(39)
Contractual adjustments, payments/returns relating to sales in the current year	(1,240)	(1,079)
Contractual adjustments, payments/returns relating to sales in the prior year	(202)	(85)
Contractual adjustments, ending balance	182	253
Government Rebates
Government rebates, beginning balance	1,354	1,084
Government rebates, current provisions relating to sales in the current year	2,917	2,593
Government rebates, adjustments relating to prior years	(892)	(711)
Government rebates, payments/returns relating to sales in the current year	(1,643)	(1,239)
Government rebates, payments/returns relating to sales in the prior years	(462)	(373)
Government rebates, ending balance	1,274	1,354
Returns
Returns, beginning balance	489	232
Returns, current provisions relating to sales in the current year	557	399
Returns, adjustments relating to prior years	0	(45)
Returns, payments/returns relating to sales in the current year	0	0
Returns, payments/returns relating to sales in the prior years	(6)	(97)
Returns, ending balance	1,040	489
Total
Total revenue-related reserves	2,496	2,096	$ 1,472
Total allowances and reserves, current provisions relating to sales in the current year	4,896	4,292
Total allowances and reserves, adjustments relating to prior years	(943)	(795)
Total allowances and reserves, payments/returns relating to sales in the current year	(2,883)	(2,318)
Total allowances and reserves, payments/returns relating to sales in the prior years	$ (670)	$ (555)

AGIOS PHARMACEUTICALS, INC. 10-K