(Loss) Earnings per Share - Computation of Basic and Diluted Earnings (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Numerator:
Net (loss) income attributable to Amneal Pharmaceuticals, Inc.	$ (11,996)	$ (16,902)	$ 103,071	$ (64,783)
Denominator:
Weighted-average shares outstanding - basic (in shares)	147,392	128,016	147,286	127,852
Effect of dilutive securities:
Weighted-average shares outstanding - diluted (in shares)	147,392	128,016	148,309	127,852
Net (loss) earnings per share attributable to Amneal Pharmaceuticals, Inc.'s common stockholders:
Basic (in usd per share)	$ (0.08)	$ (0.13)	$ 0.70	$ (0.51)
Diluted (in usd per share)	$ (0.08)	$ (0.13)	$ 0.69	$ (0.51)
Stock options
Effect of dilutive securities:
Effect of dilutive securities (in shares)	0	0	278	0
Restricted stock units
Effect of dilutive securities:
Effect of dilutive securities (in shares)	0	0	745	0
Class A Common Stock
Net (loss) earnings per share attributable to Amneal Pharmaceuticals, Inc.'s common stockholders:
Conversion of Class B-1 Common Stock (in shares)					12,300
Class B-1 Common Stock
Net (loss) earnings per share attributable to Amneal Pharmaceuticals, Inc.'s common stockholders:
Conversion of Class B-1 Common Stock (in shares)		12,300