Segment Information (Summary of Financial Information by Segment) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue
Hosted services – Business		$ 50,197	$ 41,996	$ 100,809	$ 81,677
Hosted services – Consumer		3,862	4,539	7,559	8,448
Professional services		5,275	4,552	10,736	8,790
Revenue		59,334	51,087	119,104	98,915
Cost of revenue	[1],[2],[3]	17,887	13,161	34,141	24,896
Sales and marketing	[2],[3]	24,382	20,077	48,676	38,472
Amortization of purchased intangibles	[2],[3]	1,178	206	2,490	396
Unallocated corporate expenses		23,568	19,124	43,533	37,573
Operating income (loss)		(7,681)	(1,481)	(9,736)	(2,422)
Business [Member]
Revenue
Hosted services – Business		50,197	41,996	100,809	81,677
Professional services		5,275	4,552	10,736	8,790
Revenue		55,472	46,548	111,545	90,467
Cost of revenue		17,271	12,483	32,887	23,627
Sales and marketing		22,617	18,799	45,531	35,717
Amortization of purchased intangibles		1,178	206	2,490	396
Operating income (loss)		14,406	15,060	30,637	30,727
Consumer [Member]
Revenue
Hosted services – Consumer		3,862	4,539	7,559	8,448
Revenue		3,862	4,539	7,559	8,448
Cost of revenue		616	678	1,254	1,269
Sales and marketing		1,765	1,278	3,145	2,755
Operating income (loss)		1,481	2,583	3,160	4,424
Corporate [Member]
Revenue
Unallocated corporate expenses		23,568	19,124	43,533	37,573
Operating income (loss)		$ (23,568)	$ (19,124)	$ (43,533)	$ (37,573)

[1] 3) Amounts include amortization expense as follows: Cost of revenue $839 and $869 for the three months ended June 30, 2015 and 2014, respectively

[2] Amounts include depreciation expense as follows: Cost of revenue $2,323 and $1,646 for the three months ended June 30, 2015 and 2014, respectively and $4,225 and $3,044 for the six months ended June 30, 2015 and 2014, respectively, Sales and marketing $314 and $201 for the three months ended June 30, 2015 and 2014, respectively and $565 and $408 for the six months ended June 30, 2015 and 2014, respectively, Product development $209 and $172 for the three months ended June 30, 2015 and 2014, respectively and $397 and $349 for the six months ended June 30, 2015 and 2014, respectively, and General and administrative $236 and $214 for the three months ended June 30, 2015 and 2014, respectively and $473 and $414 for the six months ended June 30, 2015 and 2014, respectively.

[3] Amounts include stock compensation expense as follows: Cost of revenue $476 and $484 for the three months ended June 30, 2015 and 2014, respectively and $804 and $844 for the six months ended June 30, 2015 and 2014, respectively, Sales and marketing $1,937 and $923 for the three months ended June 30, 2015 and 2014, respectively and $1,532 and $1,737 for the six months ended June 30, 2015 and 2014, respectively, Product development $953 and $931 for the three months ended June 30, 2015 and 2014, respectively and $1,892 and $1,611 for the six months ended June 30, 2015 and 2014, respectively, and General and administrative $746 and $869 for the three months ended June 30, 2015 and 2014, respectively and $1,678 and $1,712 for the six months ended June 30, 2015 and 2014, respectively.