Investments Available-for-sale investments (Tables)

3 Months Ended

Mar. 31, 2018

Schedule of Available-for-sale Securities [Line Items]

Schedule of Available-for-sale Securities Reconciliation [Table Text Block]

The following table summarizes the gross unrealized gains and losses and fair values for investments classified as available-for-sale investments (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
March 31, 2018
Corporate debt securities	$	22,745	$	—	$	(2,500	)	$	20,245
Total	$	22,745	$	—	$	(2,500	)	$	20,245
December 31, 2017
Corporate debt securities	$	22,745	$	—	$	—		$	22,745
Total	$	22,745	$	—	$	—		$	22,745

Investments Classified by Contractual Maturity Date [Table Text Block]

The following table summarizes j2 Global’s corporate debt securities designated as available-for-sale, classified by the contractual maturity date of the security (in thousands):

	March 31, 2018		December 31, 2017
Due within 1 year	$	—	$	—
Due within more than 1 year but less than 5 years	20,245		22,745
Due within more than 5 years but less than 10 years	—		—
Due 10 years or after	—		—
Total	$	20,245	$	22,745

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block]

The following tables present gross unrealized losses and fair values for those investments that were in an unrealized loss position as of March 31, 2018 and December 31, 2017, aggregated by investment category and the length of time that individual securities have been in a continuous loss position (in thousands):

	As of March 31, 2018
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate debt securities	$	20,245	$	(2,500	)	$	—	$	—	$	20,245	$	(2,500	)
Total	$	20,245	$	(2,500	)	$	—	$	—	$	20,245	$	(2,500	)
	As of December 31, 2017
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Corporate debt securities	$	22,745	$	—		$	—	$	—	$	22,745	$	—
Total	$	22,745	$	—		$	—	$	—	$	22,745	$	—