Segment Information (Summary of Financial Information by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue
Hosted services – Business	$ 50,957	$ 43,702	$ 151,767	$ 125,378
Hosted services – Consumer	3,661	3,992	11,219	12,441
Professional services	6,139	5,093	16,875	13,883
Revenue	60,757	52,787	179,861	151,702
Cost of revenue	16,937	13,304	51,078	38,200
Sales and marketing	23,286	20,978	71,962	59,449
Amortization of purchased intangibles	1,193	407	3,683	803
Unallocated corporate expenses	17,442	18,499	60,975	56,073
Operating income (loss)	1,899	(401)	(7,837)	(2,823)
Business [Member]
Revenue
Hosted services – Business	50,957	43,702	151,767	125,378
Professional services	6,139	5,093	16,875	13,883
Revenue	57,096	48,795	168,642	139,261
Cost of revenue	16,364	12,679	49,299	36,306
Sales and marketing	21,333	19,488	66,865	55,203
Amortization of purchased intangibles	1,193	407	3,683	803
Operating income (loss)	18,206	16,221	48,795	46,949
Consumer [Member]
Revenue
Hosted services – Consumer	3,661	3,992	11,219	12,441
Revenue	3,661	3,992	11,219	12,441
Cost of revenue	573	625	1,779	1,894
Sales and marketing	1,953	1,490	5,097	4,246
Operating income (loss)	1,135	1,877	4,343	6,301
Corporate [Member]
Revenue
Unallocated corporate expenses	17,442	18,499	60,975	56,073
Operating income (loss)	$ (17,442)	$ (18,499)	$ (60,975)	$ (56,073)