Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	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, 2014	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Common Share
Net Income Attributable to Lannett Company, Inc	$ 23,535	$ 22,995	$ 16,566	$ (5,995)	$ 3,563	$ 3,947	$ 2,881	$ 206	$ 1,415	$ 1,718	$ 609	$ 206	$ 57,101	$ 13,317	$ 3,948
Basic weighted average common shares outstanding													33,663,589	28,467,598	28,263,335
Effect of potentially dilutive options and restricted stock awards (in shares)													1,529,787	475,335	145,097
Diluted weighted average common shares outstanding													35,193,376	28,942,933	28,408,432
Earnings (loss) per common share attributable to Lannett Company Inc
Basic (in dollars per share)	$ 0.66	$ 0.66	$ 0.48	$ (0.20)	$ 0.12	$ 0.14	$ 0.10	$ 0.10	$ 0.05	$ 0.06	$ 0.02	$ 0.01	$ 1.70	$ 0.47	$ 0.14
Diluted (in dollars per share)	$ 0.64	$ 0.63	$ 0.46	$ (0.20)	$ 0.12	$ 0.14	$ 0.10	$ 0.10	$ 0.05	$ 0.06	$ 0.02	$ 0.01	$ 1.62	$ 0.46	$ 0.14
Anti-dilutive shares excluded in the computation of diluted earnings per share													18,000	1,000,000	2,300,000