CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Stockholders' Equity Attributable to Lannett Co., Inc	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (loss)	Treasury Stock	Noncontrolling Interest	Total
Balance at Jun. 30, 2016	$ 554,049	$ 37	$ 283,301	$ 278,355	$ (295)	$ (7,349)	$ 408	$ 554,457
Balance (in shares) at Jun. 30, 2016		37,150
Increase (Decrease) in Shareholders' Equity
Shares issued in connection with share-based compensation plans	2,818		2,818					2,818
Shares issued in connection with share-based compensation plans (in shares)		378
Share-based compensation	7,719		7,719					7,719
Purchase of noncontrolling interest	(1,058)		(1,058)				(442)	(1,500)
Purchase of treasury stock	(1,898)					(1,898)		(1,898)
Other comprehensive income (loss), net of income tax	73				73			73
Net income (loss)	(581)			(581)			$ 34	(547)
Balance at Jun. 30, 2017	561,122	$ 37	292,780	277,774	(222)	(9,247)		561,122
Balance (in shares) at Jun. 30, 2017		37,528
Increase (Decrease) in Shareholders' Equity
Shares issued in connection with share-based compensation plans	4,142	$ 1	4,141					4,142
Shares issued in connection with share-based compensation plans (in shares)		729
Share-based compensation	9,896		9,896					9,896
Purchase of treasury stock	(4,642)					(4,642)		(4,642)
Other comprehensive income (loss), net of income tax	(293)				(293)			(293)
Net income (loss)	28,690			28,690				28,690
Balance at Jun. 30, 2018	598,915	$ 38	306,817	306,464	(515)	(13,889)		598,915
Balance (in shares) at Jun. 30, 2018		38,257
Increase (Decrease) in Shareholders' Equity
Shares issued in connection with share-based compensation plans	1,180	$ 1	1,179					1,180
Shares issued in connection with share-based compensation plans (in shares)		713
Share-based compensation	9,027		9,027					9,027
Purchase of treasury stock	(592)					(592)		(592)
Other comprehensive income (loss), net of income tax	(100)				(100)			(100)
Net income (loss)	(272,107)			(272,107)				(272,107)
Balance at Jun. 30, 2019	334,041	$ 39	$ 317,023	32,075	$ (615)	$ (14,481)		334,041
Balance (in shares) at Jun. 30, 2019		38,970
Increase (Decrease) in Shareholders' Equity
ASC 606 adjustment | ASU 2014-09	$ (2,282)			$ (2,282)				$ (2,282)