Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 14,951	$ 59,475	$ 170,714
Unrealized gain (loss) on investments, net of tax	2,397	61	(1,569)
Comprehensive income	17,348	59,536	169,145
Comprehensive loss attributable to noncontrolling interest	(5,977)	(5,556)	(5,506)
Total comprehensive income attributable to InterDigital, Inc.	$ 23,325	$ 65,092	$ 174,651