Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Common Share
Net Income (Loss) Attributable to Lannett Company, Inc	$ 3,563	$ 3,947	$ 2,881	$ 2,926	$ 1,415	$ 1,718	$ 609	$ 206	$ (1,864)	$ (362)	$ 2,353	$ (404)	$ 13,317	$ 3,948	$ (277)
Basic weighted average common shares outstanding													28,467,598	28,263,335	26,758,552
Effect of potentially dilutive options and restricted stock awards (in shares)													475,335	145,097
Diluted weighted average common shares outstanding													28,942,933	28,408,432	26,758,552
Earnings per common share attributable to the entity:
Basic (in dollars per share)	$ 0.12	$ 0.14	$ 0.10	$ 0.10	$ 0.05	$ 0.06	$ 0.02	$ 0.01	$ (0.07)	$ (0.01)	$ 0.09	$ (0.02)	$ 0.47	$ 0.14	$ (0.01)
Diluted (in dollars per share)	$ 0.12	$ 0.14	$ 0.10	$ 0.10	$ 0.05	$ 0.06	$ 0.02	$ 0.01	$ (0.07)	$ (0.01)	$ 0.09	$ (0.02)	$ 0.46	$ 0.14	$ (0.01)
Anti-dilutive shares excluded in the computation of diluted earnings per share													1,000,000	2,300,000	2,100,000