Condensed Consolidating Financials Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net cash (used in) provided by operating activities	$ 282,387	$ 229,061	$ 177,231
Cash flows from investing activities:
Maturity of certificates of deposit	0	65	14,520
Purchase of certificates of deposit	0	(62)	(65)
Maturity of available-for-sale investments	241,817	121,687	110,363
Purchase of available-for-sale investments	(80,918)	(135,832)	(138,452)
Purchases of property and equipment	(24,746)	(17,297)	(11,829)
Proceeds from sale of assets	0	0	608
Acquisition of businesses, net of cash received	(580,691)	(302,809)	(245,278)
Purchases of intangible assets	(4,321)	(1,455)	(5,336)
Investment in subsidiaries		0	0
Intercompany	0	0
Net cash used in investing activities	(448,859)	(335,703)	(275,469)
Cash flows from financing activities:
Issuance of long-term debt	0	0	402,500
Debt issuance costs	0	0	(11,991)
Proceeds from line of credit, net	178,710	0	0
Repurchases of common and restricted stock	(56,496)	(3,674)	(5,663)
Issuance of common stock under employee stock purchase plan	254	260	265
Exercise of stock options	3,570	4,958	6,621
Dividends paid	(65,835)	(58,826)	(52,269)
Excess tax benefits from share-based compensation	2,271	4,486	5,512
Deferred payments for acquisitions	(20,832)	(14,271)	(16,512)
Other	(492)	(296)	(933)
Intercompany	0	0	0
Net cash (used in) provided by financing activities	41,150	(67,363)	327,530
Effect of exchange rate changes on cash and cash equivalents	(6,258)	(4,128)	(3,430)
Net change in cash and cash equivalents	(131,580)	(178,133)	225,862
Cash and cash equivalents at beginning of period	255,530	433,663	207,801
Cash and cash equivalents at end of period	123,950	255,530	433,663
Consolidating Adjustments
Net cash (used in) provided by operating activities	0	0	0
Cash flows from investing activities:
Maturity of certificates of deposit		0	0
Purchase of certificates of deposit		0	0
Maturity of available-for-sale investments	0	0	0
Purchase of available-for-sale investments	0	0	0
Purchases of property and equipment	0	0	0
Proceeds from sale of assets			0
Acquisition of businesses, net of cash received	0	0	0
Purchases of intangible assets	0	0	0
Investment in subsidiaries		0	23,821
Intercompany	0	0
Net cash used in investing activities	0	0	23,821
Cash flows from financing activities:
Issuance of long-term debt			0
Debt issuance costs			0
Proceeds from line of credit, net	0
Repurchases of common and restricted stock	0	0	0
Issuance of common stock under employee stock purchase plan	0	0	0
Exercise of stock options	0	0	0
Dividends paid	0	0	0
Excess tax benefits from share-based compensation	0	0	0
Deferred payments for acquisitions	0	0	0
Other	0	0	0
Intercompany	0	0	(23,821)
Net cash (used in) provided by financing activities	0	0	(23,821)
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0		0
Cash and cash equivalents at end of period	0	0
j2 Global, Inc.
Net cash (used in) provided by operating activities	(60,383)	(29,406)	(65)
Cash flows from investing activities:
Maturity of certificates of deposit		65	0
Purchase of certificates of deposit		(62)	0
Maturity of available-for-sale investments	241,817	121,687	40,211
Purchase of available-for-sale investments	(80,918)	(135,832)	(81,061)
Purchases of property and equipment	0	0	0
Proceeds from sale of assets			0
Acquisition of businesses, net of cash received	0	0	0
Purchases of intangible assets	0	0	0
Investment in subsidiaries		0	0
Intercompany	0	(53,317)
Net cash used in investing activities	160,899	(67,459)	(40,850)
Cash flows from financing activities:
Issuance of long-term debt			402,500
Debt issuance costs			(11,991)
Proceeds from line of credit, net	178,710
Repurchases of common and restricted stock	(56,495)	(3,674)	(930)
Issuance of common stock under employee stock purchase plan	254	260	142
Exercise of stock options	3,570	4,958	1,374
Dividends paid	(65,835)	(58,826)	(26,967)
Excess tax benefits from share-based compensation	2,271	4,486	86
Deferred payments for acquisitions	0	0	0
Other	0	0	0
Intercompany	(194,358)	(29,835)	(96,509)
Net cash (used in) provided by financing activities	(131,883)	(82,631)	267,705
Effect of exchange rate changes on cash and cash equivalents	(214)	8,222	0
Net change in cash and cash equivalents	(31,581)	(171,274)	226,790
Cash and cash equivalents at beginning of period	55,516	226,790	0
Cash and cash equivalents at end of period	23,935	55,516	226,790
j2 Cloud Services
Net cash (used in) provided by operating activities	65,429	70,905	59,544
Cash flows from investing activities:
Maturity of certificates of deposit		0	8,210
Purchase of certificates of deposit		0	0
Maturity of available-for-sale investments	0	0	53,563
Purchase of available-for-sale investments	0	0	(57,391)
Purchases of property and equipment	(2,513)	(1,645)	(2,866)
Proceeds from sale of assets			608
Acquisition of businesses, net of cash received	(7,609)	0	(2,083)
Purchases of intangible assets	(106)	57	(2,949)
Investment in subsidiaries		0	(23,821)
Intercompany	0	53,317
Net cash used in investing activities	(10,228)	51,729	(26,729)
Cash flows from financing activities:
Issuance of long-term debt			0
Debt issuance costs			0
Proceeds from line of credit, net	0
Repurchases of common and restricted stock	0	0	(4,733)
Issuance of common stock under employee stock purchase plan	0	0	123
Exercise of stock options	0	0	5,193
Dividends paid	0	0	(25,302)
Excess tax benefits from share-based compensation	0	0	4,803
Deferred payments for acquisitions	(1,547)	(2,000)	0
Other	0	0	0
Intercompany	(40,596)	(144,516)	(10,495)
Net cash (used in) provided by financing activities	(42,143)	(146,516)	(30,411)
Effect of exchange rate changes on cash and cash equivalents	(84)	(2,953)	0
Net change in cash and cash equivalents	12,974	(26,835)	2,404
Cash and cash equivalents at beginning of period	9,975	36,810	34,406
Cash and cash equivalents at end of period	22,949	9,975	36,810
Non-guarantor Subsidiaries
Net cash (used in) provided by operating activities	277,341	187,562	117,752
Cash flows from investing activities:
Maturity of certificates of deposit		0	6,310
Purchase of certificates of deposit		0	(65)
Maturity of available-for-sale investments	0	0	16,589
Purchase of available-for-sale investments	0	0	0
Purchases of property and equipment	(22,233)	(15,652)	(8,963)
Proceeds from sale of assets			0
Acquisition of businesses, net of cash received	(573,082)	(302,809)	(243,195)
Purchases of intangible assets	(4,215)	(1,512)	(2,387)
Investment in subsidiaries		0	0
Intercompany	0	0
Net cash used in investing activities	(599,530)	(319,973)	(231,711)
Cash flows from financing activities:
Issuance of long-term debt			0
Debt issuance costs			0
Proceeds from line of credit, net	0
Repurchases of common and restricted stock	(1)	0	0
Issuance of common stock under employee stock purchase plan	0	0	0
Exercise of stock options	0	0	54
Dividends paid	0	0	0
Excess tax benefits from share-based compensation	0	0	623
Deferred payments for acquisitions	(19,285)	(12,271)	(16,512)
Other	(492)	(296)	(933)
Intercompany	234,954	174,351	130,825
Net cash (used in) provided by financing activities	215,176	161,784	114,057
Effect of exchange rate changes on cash and cash equivalents	(5,960)	(9,397)	(3,430)
Net change in cash and cash equivalents	(112,973)	19,976	(3,332)
Cash and cash equivalents at beginning of period	190,039	170,063	173,395
Cash and cash equivalents at end of period	$ 77,066	$ 190,039	$ 170,063