Acquisitions (Assets Acquired and Liabilities Assumed and Divested) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Jan. 10, 2017	Dec. 31, 2016	Apr. 27, 2016	Mar. 14, 2016	Jan. 07, 2016
Assets Acquired
Goodwill	$ 82,803		$ 69,097
Omtool, Ltd [Member]
Assets Acquired
Cash		$ 2,957
Accounts receivable		784
Other current assets		405
Property and equipment		63
Goodwill		13,574
Other assets		33
Total assets acquired		25,956
Liabilities Assumed
Accounts payable		(219)
Accrued expense and other		(906)
Deferred revenue		(2,618)
Total liabilities assumed		(3,743)
Total consideration		22,213
Omtool, Ltd [Member] | Customer Relationships [Member]
Assets Acquired
Intangible assets		3,520
Omtool, Ltd [Member] | Trade Name [Member]
Assets Acquired
Intangible assets		170
Omtool, Ltd [Member] | Technology [Member]
Assets Acquired
Intangible assets		$ 4,450
API [Member]
Assets Acquired
Cash				$ 125
Accounts receivable				821
Other current assets				54
Property and equipment				68
Goodwill				3,420
Other assets				89
Total assets acquired				6,847
Liabilities Assumed
Accounts payable				(11)
Accrued expense and other				(137)
Deferred revenue				(1,699)
Total liabilities assumed				(1,847)
Total consideration				5,000
API [Member] | Customer Relationships [Member]
Assets Acquired
Intangible assets				1,420
API [Member] | Trade Name [Member]
Assets Acquired
Intangible assets				40
API [Member] | Technology [Member]
Assets Acquired
Intangible assets				$ 810
Hipcricket [Member]
Assets Acquired
Cash					$ 0
Accounts receivable					1,226
Other current assets					273
Property and equipment					0
Goodwill					8,531
Other assets					0
Total assets acquired					12,000
Liabilities Assumed
Accounts payable					(44)
Accrued expense and other					0
Deferred revenue					(356)
Total liabilities assumed					(400)
Total consideration					11,600
Hipcricket [Member] | Customer Relationships [Member]
Assets Acquired
Intangible assets					1,000
Hipcricket [Member] | Trade Name [Member]
Assets Acquired
Intangible assets					70
Hipcricket [Member] | Technology [Member]
Assets Acquired
Intangible assets					$ 900
Website Analytic Business [Member]
Assets Acquired
Cash						$ 365
Accounts receivable						199
Other current assets						55
Property and equipment						5
Goodwill						13,104
Other assets						6
Total assets acquired						16,184
Liabilities Assumed
Accounts payable						0
Accrued expense and other						(254)
Deferred revenue						(910)
Total liabilities assumed						(1,164)
Total consideration						15,020
Website Analytic Business [Member] | Customer Relationships [Member]
Assets Acquired
Intangible assets						970
Website Analytic Business [Member] | Trade Name [Member]
Assets Acquired
Intangible assets						70
Website Analytic Business [Member] | Technology [Member]
Assets Acquired
Intangible assets						$ 1,410