Condensed Consolidating Financials Condensed Consolidating Comprehensive Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Income	$ 43,157	$ 45,569	$ 33,770	$ 29,943	$ 35,467	$ 37,375	$ 38,916	$ 21,878	$ 152,439	$ 133,636	$ 125,327
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment									(23,076)	(15,058)	(14,694)
Change in fair value on available-for-sale investments, net of tax expense (benefit)									(2,449)	(6,939)	3,332
Other comprehensive loss, net of tax									(25,525)	(21,997)	(11,362)
Comprehensive Income									126,914	111,639	113,965
Consolidating Adjustments
Net Income									(257,746)	(268,036)	(212,889)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment									0	0	0
Change in fair value on available-for-sale investments, net of tax expense (benefit)									0	0	0
Other comprehensive loss, net of tax									0	0	0
Comprehensive Income									(257,746)	(268,036)	(212,889)
j2 Global, Inc.
Net Income									152,439	133,636	125,327
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment									0	0	0
Change in fair value on available-for-sale investments, net of tax expense (benefit)									(2,449)	(6,939)	15
Other comprehensive loss, net of tax									(2,449)	(6,939)	15
Comprehensive Income									149,990	126,697	125,342
j2 Cloud Services
Net Income									145,094	151,894	135,838
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment									0	0	(478)
Change in fair value on available-for-sale investments, net of tax expense (benefit)									0	0	3,307
Other comprehensive loss, net of tax									0	0	2,829
Comprehensive Income									145,094	151,894	138,667
Non-guarantor Subsidiaries
Net Income									112,652	116,142	77,051
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment									(23,076)	(15,058)	(14,216)
Change in fair value on available-for-sale investments, net of tax expense (benefit)									0	0	10
Other comprehensive loss, net of tax									(23,076)	(15,058)	(14,206)
Comprehensive Income									$ 89,576	$ 101,084	$ 62,845