Summary of Operations and Significant Accounting Policies (Summary of Financial Information by Segment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Hosted services - Business	$ 36,634	$ 32,151	$ 72,778	$ 63,390
Hosted services - Consumer	3,776	3,961	7,395	7,809
Professional services	2,819	2,393	5,552	4,065
Total revenue	43,229	38,505	85,725	75,264
Cost of revenue	10,612	8,492	20,746	16,414
Sales and marketing	15,499	13,017	29,977	24,107
Amortization of intangibles	224	11	448	87
Unallocated corporate expenses	18,882	16,561	37,140	29,344
(Loss) income from operations	(1,988)	424	(2,586)	5,312
Corporate [Member]
Segment Reporting Information [Line Items]
Hosted services - Business
Hosted services - Consumer
Professional services
Total revenue
Cost of revenue
Sales and marketing
Amortization of intangibles
Unallocated corporate expenses	18,882	16,561	37,140	29,344
(Loss) income from operations	(18,882)	(16,561)	(37,140)	(29,344)
Business [Member]
Segment Reporting Information [Line Items]
Hosted services - Business	36,634	32,151	72,778	63,390
Hosted services - Consumer
Professional services	2,819	2,393	5,552	4,065
Total revenue	39,453	34,544	78,330	67,455
Cost of revenue	9,974	7,939	19,510	15,306
Sales and marketing	14,243	11,624	27,449	21,114
Amortization of intangibles	224	11	448	87
Unallocated corporate expenses
(Loss) income from operations	15,012	14,970	30,923	30,948
Consumer [Member]
Segment Reporting Information [Line Items]
Hosted services - Business
Hosted services - Consumer	3,776	3,961	7,395	7,809
Professional services
Total revenue	3,776	3,961	7,395	7,809
Cost of revenue	638	553	1,236	1,108
Sales and marketing	1,256	1,393	2,528	2,993
Amortization of intangibles
Unallocated corporate expenses
(Loss) income from operations	$ 1,882	$ 2,015	$ 3,631	$ 3,708