Acquisitions (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Apr. 27, 2016	Mar. 14, 2016	Jan. 07, 2016	Dec. 31, 2015	Nov. 13, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill	$ 69,097				$ 47,422		$ 45,146	$ 33,630
Advanced Processing & Imaging, Inc. [Member]
Business Acquisition [Line Items]
Cash		$ 125
Accounts receivable		821
Other current assets		54
Canadian tax credit receivable		0
Property and equipment		68
Goodwill		3,420
Other assets		89
Total assets acquired		6,847
Accounts payable		(11)
Accrued expense and other		(137)
Deferred tax liabilities		0
Deferred revenue		(1,699)
Canadian tax credit liability to seller		0
Total liabilities assumed		(1,847)
Total consideration		5,000
Advanced Processing & Imaging, Inc. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets		1,420
Advanced Processing & Imaging, Inc. [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets		40
Advanced Processing & Imaging, Inc. [Member] | Technology [Member]
Business Acquisition [Line Items]
Intangible assets		$ 810
California-based Website Analytic Provider [Member]
Business Acquisition [Line Items]
Cash				$ 365
Accounts receivable				199
Other current assets				55
Canadian tax credit receivable				0
Property and equipment				5
Goodwill				13,104
Other assets				6
Total assets acquired				16,184
Accounts payable				0
Accrued expense and other				(254)
Deferred tax liabilities				0
Deferred revenue				(910)
Canadian tax credit liability to seller				0
Total liabilities assumed				(1,164)
Total consideration				15,020
California-based Website Analytic Provider [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets				970
California-based Website Analytic Provider [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets				70
California-based Website Analytic Provider [Member] | Technology [Member]
Business Acquisition [Line Items]
Intangible assets				$ 1,410
Hipcricket, Inc. [Member]
Business Acquisition [Line Items]
Cash			$ 0
Accounts receivable			1,226
Other current assets			273
Canadian tax credit receivable			0
Property and equipment			0
Goodwill			8,531
Other assets			0
Total assets acquired			12,000
Accounts payable			(44)
Accrued expense and other			0
Deferred tax liabilities			0
Deferred revenue			(356)
Canadian tax credit liability to seller			0
Total liabilities assumed			(400)
Total consideration			11,600
Hipcricket, Inc. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets			1,000
Hipcricket, Inc. [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets			70
Hipcricket, Inc. [Member] | Technology [Member]
Business Acquisition [Line Items]
Intangible assets			$ 900
Ultriva, Inc. [Member]
Business Acquisition [Line Items]
Cash						$ 372
Accounts receivable						689
Other current assets						52
Canadian tax credit receivable						0
Property and equipment						16
Goodwill						4,739
Other assets						32
Total assets acquired						8,820
Accounts payable						(196)
Accrued expense and other						(284)
Deferred tax liabilities						0
Deferred revenue						(760)
Canadian tax credit liability to seller						0
Total liabilities assumed						(1,240)
Total consideration						7,580
Ultriva, Inc. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets						1,820
Ultriva, Inc. [Member] | Trade Names [Member]
Business Acquisition [Line Items]
Intangible assets						140
Ultriva, Inc. [Member] | Technology [Member]
Business Acquisition [Line Items]
Intangible assets						$ 960