Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings (Accumulated Deficit)	Other Comprehensive Loss
BEGINNING BALANCE at Dec. 31, 2015	$ 621,565	$ 458,659	$ 180,048	$ (17,142)
BEGINNING BALANCE (in Shares) at Dec. 31, 2015		119,427,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
(Loss) income from operations used for basic earnings per share	184,243		184,243
Common stock repurchases	$ (45,000)		(45,000)
Common stock repurchases (in Shares)	(1,800,000)	(1,808,000)
Exercise of stock options	$ 13,953	$ 13,953
Exercise of stock options (in Shares)		1,792,000
Restricted stock units	4,091	$ 4,091
Restricted stock units (in Shares)		184,000
Stock-based compensation expense	11,321	$ 11,321
Foreign currency translation loss	(1,941)			(1,941)
Excess tax benefit – stock compensation, Stock compensation plans withholdings for employee taxes	(4,158)	$ (4,158)
Excess tax benefit – stock compensation, Stock compensation plans withholdings for employee taxes (in Shares)		(138,000)
Unrealized holding loss on available-for-sale securities	740			740
Convertible note conversions	43,215	$ 43,215
Convertible note conversions (in Shares)		4,933,000
Akorn AG pension liability adjustment	(3,624)			(3,624)
Other	(5,221)	$ (5,221)
ENDING BALANCE at Dec. 31, 2016	819,184	$ 521,860	319,291	(21,967)
ENDING BALANCE (in Shares) at Dec. 31, 2016		124,390,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
(Loss) income from operations used for basic earnings per share	$ (24,550)		(24,550)
Common stock repurchases (in Shares)	0
Exercise of stock options	$ 9,673	$ 9,673
Exercise of stock options (in Shares)		625,000
Restricted stock units	7,736	$ 7,736
Restricted stock units (in Shares)		138,000
Stock-based compensation expense	13,282	$ 13,282
Foreign currency translation loss	6,150			6,150
Excess tax benefit – stock compensation, Stock compensation plans withholdings for employee taxes	(2,079)	$ (2,079)
Excess tax benefit – stock compensation, Stock compensation plans withholdings for employee taxes (in Shares)		(62,000)
Unrealized holding loss on available-for-sale securities	267			267
Akorn AG pension liability adjustment	1,582			1,582
ENDING BALANCE at Dec. 31, 2017	$ 831,245	$ 550,472	294,741	(13,968)
ENDING BALANCE (in Shares) at Dec. 31, 2017	125,090,522	125,091,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
(Loss) income from operations used for basic earnings per share	$ (401,909)
Common stock repurchases (in Shares)	0
Exercise of stock options	$ 546	$ 546
Exercise of stock options (in Shares)		22,000
Employee stock purchase plan issuances	2,809	$ 2,809
Employee stock purchase plan issuances (in Shares)		146,000
Restricted stock units	11,673	$ 11,673
Restricted stock units (in Shares)		288,000
Stock-based compensation expense	9,830	$ 9,830
Foreign currency translation loss	(8,001)			(8,001)
Stock compensation plan withholdings for employee taxes	(777)	$ (777)
Stock compensation plan withholdings for employee taxes (in Shares)		(55,000)
Unrealized holding loss on available-for-sale securities	(21)			(21)
Akorn AG pension liability adjustment	(1,529)			(1,529)
ENDING BALANCE at Dec. 31, 2018	$ 443,866	$ 574,553	$ (107,168)	$ (23,519)
ENDING BALANCE (in Shares) at Dec. 31, 2018	125,492,373	125,492,000