Acquisitions (Components of Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended	0 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Nov. 07, 2014	Jun. 02, 2014
Contact At Once! [Member]
Business Acquisition [Line Items]
Intangible assets			$ 20,400
Synchronite, LLC [Member]
Business Acquisition [Line Items]
Intangible assets	1,450			1,451
Technology [Member]
Business Acquisition [Line Items]
Weighted average useful life	5 years 3 months 18 days	5 years 3 months 18 days
Technology [Member] | Contact At Once! [Member]
Business Acquisition [Line Items]
Weighted average useful life			96 months
Intangible assets			8,400
Technology [Member] | Synchronite, LLC [Member]
Business Acquisition [Line Items]
Weighted average useful life				120 months
Intangible assets				1,082
Trade Names [Member]
Business Acquisition [Line Items]
Weighted average useful life	2 years 9 months 12 days	2 years 9 months 12 days
Trade Names [Member] | Contact At Once! [Member]
Business Acquisition [Line Items]
Weighted average useful life			12 months
Intangible assets			500
Trade Names [Member] | Synchronite, LLC [Member]
Business Acquisition [Line Items]
Weighted average useful life				48 months
Intangible assets				62
Customer Relationships [Member] | Contact At Once! [Member]
Business Acquisition [Line Items]
Weighted average useful life			120 months
Intangible assets			10,700
Customer Relationships [Member] | Synchronite, LLC [Member]
Business Acquisition [Line Items]
Weighted average useful life				84 months
Intangible assets				247
Non-compete Agreements [Member]
Business Acquisition [Line Items]
Weighted average useful life	2 years 3 months 12 days	2 years 3 months 12 days
Non-compete Agreements [Member] | Contact At Once! [Member]
Business Acquisition [Line Items]
Weighted average useful life			36 months
Intangible assets			800
Non-compete Agreements [Member] | Synchronite, LLC [Member]
Business Acquisition [Line Items]
Weighted average useful life				36 months
Intangible assets				$ 60