Concentration of Credit Risk and Fair Value of Financial Assets and Financial Liabilities (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jul. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Mar. 11, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		$ 936,302	$ 959,457
Contingent consideration liability			19,800
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net loss on sale of investments		2,600	8,400
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		757,098	488,733
Contingent consideration liability			0
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		179,204	470,724
Contingent consideration liability			0
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		0	0
Contingent consideration liability			19,800
Technicolor Patent Acquisition
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability			19,800	$ 18,616
Gain on contingent consideration	$ 20,500	20,500
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		19,800
Changes in fair value recognized in the consolidated statements of income		710
Derecognition of contingent consideration liability as a Level 3 fair value measurement		(20,510)
Ending balance		0	19,800
Carrying value of technicolor patent acquisition long-term debt				$ 17,717
Technicolor Patent Acquisition | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability			0
Technicolor Patent Acquisition | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability			0
Technicolor Patent Acquisition | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability			19,800
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value		23,305	19,100
Carrying value of technicolor patent acquisition long-term debt		21,101	18,428
Money market funds and demand deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		757,098	488,733
Money market funds and demand deposits | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		757,098	488,733
Money market funds and demand deposits | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		0	0
Money market funds and demand deposits | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		0	0
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value			14,548
Commercial paper | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value			0
Commercial paper | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value			14,548
Commercial paper | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value			0
US treasury and government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		105,702	289,576
US treasury and government | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		0	0
US treasury and government | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		105,702	289,576
US treasury and government | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		0	0
Corporate Bonds and Asset Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		73,502	166,600
Corporate Bonds and Asset Backed Securities | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		0	0
Corporate Bonds and Asset Backed Securities | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		73,502	166,600
Corporate Bonds and Asset Backed Securities | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets fair value		0	0
ZTE Corporation | Patents
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of patent		14,000
Sony | Patents
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of patent			$ 22,500
LG | Patents
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of patent					$ 19,700
Revenue Volatility | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.350
Revenue Volatility | Weighted Average | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.350
Credit Risk Discount Rate | Maximum | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.080
Credit Risk Discount Rate | Minimum | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.062
Credit Risk Discount Rate | Weighted Average | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.071
Risk Adjusted Discount Rate For Revenue | Maximum | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.142
Risk Adjusted Discount Rate For Revenue | Minimum | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.135
Risk Adjusted Discount Rate For Revenue | Weighted Average | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant unobservable input			0.139
Convertible Notes 2020 | Convertible Notes 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Principal Amount		494,909				$ 316,000
Carrying Value		423,657	$ 298,951
Fair Value		$ 492,969	$ 331,595
Customer Concentration Risk | Accounts Receivable | Seven licensees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Concentration risk		73.00%
Customer Concentration Risk | Accounts Receivable | Five licensees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Concentration risk			76.00%