Segment Information (Summary of Financial Information by Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenue
Hosted services – Business	$ 38,007	$ 33,245	$ 110,785	$ 96,634
Hosted services – Consumer	3,828	3,577	11,223	11,387
Professional services	3,357	2,848	8,909	6,913
Total revenue	45,192	39,670	130,917	114,934
Cost of revenue	10,597	9,036	31,342	25,450
Sales and marketing	16,141	12,713	46,118	36,820
Amortization of purchased intangibles	224	11	672	98
Unallocated corporate expenses	19,531	15,321	56,672	44,665
(Loss) income from operations	(1,301)	2,589	(3,887)	7,901
Corporate [Member]
Revenue
Unallocated corporate expenses	19,531	15,321	56,672	44,665
(Loss) income from operations	(19,531)	(15,321)	(56,672)	(44,665)
Business [Member]
Revenue
Hosted services – Business	38,007	33,245	110,785	96,634
Professional services	3,357	2,848	8,909	6,913
Total revenue	41,364	36,093	119,694	103,547
Cost of revenue	10,014	8,539	29,524	23,845
Sales and marketing	14,664	11,502	42,113	32,616
Amortization of purchased intangibles	224	11	672	98
(Loss) income from operations	16,462	16,041	47,385	46,988
Consumer [Member]
Revenue
Hosted services – Consumer	3,828	3,577	11,223	11,387
Total revenue	3,828	3,577	11,223	11,387
Cost of revenue	583	497	1,818	1,605
Sales and marketing	1,477	1,211	4,005	4,204
(Loss) income from operations	$ 1,768	$ 1,869	$ 5,400	$ 5,578