Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

Financial assets and liabilities measured at fair value on a recurring basis were as follows (in thousands):



	Level 1		Level 2		Level 3
Assets as of December 31, 2017:
Investment at fair value (Note 7)⁽¹⁾	$	—	$	—	$	104,754

Assets as of December 31, 2016:
Short-term investments⁽¹⁾	$	19,443	$	—	$	—

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

The fair values of stock options granted during the periods presented were estimated using the Black-Scholes option-pricing model, based on the following weighted-average assumptions:



	For the Years Ended
	December 31, 2017	December 31, 2016

Risk-free interest rate	1.77%	1.1%
Term	4.37	3.06
Volatility	51%	53%
Dividend yield	—%	—%

Property and Equipment, Useful Lives

Depreciation and amortization is computed on a straight-line basis over the following estimated useful lives of the assets:



Furniture and fixtures	3 to 5 years
Computer hardware and software	3 to 5 years
Leasehold improvements	2 to 5 years (Lesser of lease term or useful life of improvement)

Schedule of Earnings Per Share, Basic and Diluted

The following table presents the weighted-average number of common shares outstanding used in the calculation of basic and diluted income per share:



	2017			2016			2015
Numerator (in thousands):
Basic and Diluted
Net income (loss) attributable to Acacia Research Corporation	$	22,180		$	(54,067	)	$	(160,036	)
Undistributed earnings allocated to participating securities	(33		)	—			—
Total dividends declared / paid	—			—			(25,434		)
Dividends attributable to common stockholders	—			—			24,740
Net income (loss) attributable to common stockholders – basic and diluted	$	22,147		$	(54,067	)	$	(160,730	)

Denominator:
Weighted-average shares used in computing net loss per share attributable to common stockholders – basic	50,495,119			50,075,847			49,505,817
Effect of potentially dilutive securities:
Common stock options and restricted stock units	196,893			—			—
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders – diluted	50,692,012			50,075,847			49,505,817
Basic and diluted net loss per common share	$	0.44		$	(1.08	)	$	(3.25	)
Anti-dilutive equity-based incentive awards excluded from the computation of diluted loss per share	4,425,187			3,682,532			71,468