Consolidated Statements of Equity - USD ($) $ in Thousands	Total	IAL	IPI	Common Stock	Common Stock IAL	Common Stock IPI	Treasury Stock	Additional Paid-in Capital	Additional Paid-in Capital IAL	Additional Paid-in Capital IPI	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)	Non-controlling Interests
Beginning balance at Dec. 31, 2015	$ 294,009			$ 6			$ (17,869)	$ 273,451			$ (1,237)	$ 39,300	$ 358
Increase (Decrease) in Stockholders' Equity
Net loss	(49,130)											(49,130)
Beginning balance (in shares) at Dec. 31, 2015				56,220,000			1,785,000
Increase (Decrease) in Stockholders' Equity
Foreign currency translation adjustment	281										281
Sale of common stock, net of issuance cost	30,090							30,090
Sale of common stock, net of issuance cost (in shares)				2,450,000
Stock issued under employee stock purchase plan	833							833
Stock issued under employee stock purchase plan (in shares)							(93,000)
Common stock issued in payment of accrued liability	0
Stock options exercised	184			$ 0				184
Stock options exercised (in shares)				114,000
Restricted stock granted (in shares)				653,000
Restricted stock forfeited (in shares)							96,000
Treasury stock purchased	$ (2,350)						$ (2,350)
Treasury stock purchased (in shares)	238,216						238,000
Stock surrendered for exercise of stock options	$ (50)						$ (50)
Stock surrendered for exercise of stock options (in shares)	3,225						3,000
Excess tax benefit related to share-based awards	$ (2,510)							(2,510)
Stock compensation expense	13,076							13,076
Stock issued in acquisition		$ 3,268							$ 3,268
Stock issued in acquisition (in shares)					248,000
Ending balance at Dec. 31, 2016	287,701			$ 6			$ (20,269)	318,392			(956)	(9,830)	358
Ending balance (in shares) at Dec. 31, 2016				59,685,000			2,029,000
Increase (Decrease) in Stockholders' Equity
Net loss	(27,395)											(27,395)
Foreign currency translation adjustment	72										72
Stock issued under employee stock purchase plan	654							654
Stock issued under employee stock purchase plan (in shares)							(113,000)
Common stock issued in payment of accrued liability	188							188
Common stock issued in payment of accrued liability (in shares)				0
Stock options exercised	$ 5,884							5,884
Stock options exercised (in shares)	663,288			663,000
Restricted stock granted (in shares)	275,029			275,000
Restricted stock forfeited (in shares)							122,000
Treasury stock purchased	$ (1,729)						$ (1,729)
Treasury stock purchased (in shares)	199,644						200,000
Stock surrendered for exercise of stock options	$ (5,863)						$ (5,863)
Stock surrendered for exercise of stock options (in shares)	478,287						478,000
Stock compensation expense	$ 10,949							10,949
Stock issued in acquisition			$ 0							$ 0
Stock issued in acquisition (in shares)						0
Repurchase of common stock	(5,203)						$ (5,203)
Repurchase of common stock (in shares)							905,000
Ending balance at Dec. 31, 2017	265,258			$ 6			$ (33,064)	336,067			(884)	(37,225)	358
Ending balance (in shares) at Dec. 31, 2017				60,623,000			3,621,000
Increase (Decrease) in Stockholders' Equity
Net loss	(70,698)											(70,340)	(358)
Foreign currency translation adjustment	(232)										(232)
Stock issued under employee stock purchase plan	341							341
Stock issued under employee stock purchase plan (in shares)							(111,000)
Common stock issued in payment of accrued liability	$ 0
Stock options exercised (in shares)	0
Restricted stock granted (in shares)	1,539,889			1,540,000
Restricted stock forfeited (in shares)							158,000
Treasury stock purchased	$ (173)						$ (173)
Treasury stock purchased (in shares)	102,333						102,000
Stock surrendered for exercise of stock options (in shares)	0
Stock compensation expense	$ 7,128							7,128
Repurchase of common stock (in shares)	0
Ending balance at Dec. 31, 2018	$ 201,624			$ 6			$ (33,237)	$ 343,536			$ (1,116)	$ (107,565)	$ 0
Ending balance (in shares) at Dec. 31, 2018				62,163,000			3,770,000