Goodwill and Other Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Components of Intangible Assets [Abstract]
Gross Carrying Value	$ 294,081		$ 294,081		$ 292,481
Accumulated Amortization	(272,520)		(272,520)		(254,375)
Net Carrying Value	21,561		21,561		38,106
Amortization of intangible assets	6,068	$ 5,986	18,145	$ 17,961
Cost of revenue [Member]
Components of Intangible Assets [Abstract]
Amortization of intangible assets	2,145	2,083	6,389	6,248
Sales and marketing [Member]
Components of Intangible Assets [Abstract]
Amortization of intangible assets	3,550	3,549	10,648	10,648
General and administrative [Member]
Components of Intangible Assets [Abstract]
Amortization of intangible assets	373	$ 354	1,108	$ 1,065
Customer relationships [Member]
Components of Intangible Assets [Abstract]
Gross Carrying Value	141,973		141,973		141,973
Accumulated Amortization	(131,789)		(131,789)		(121,141)
Net Carrying Value	10,184		10,184		20,832
Developed technology [Member]
Components of Intangible Assets [Abstract]
Gross Carrying Value	135,792		135,792		134,542
Accumulated Amortization	(128,023)		(128,023)		(121,634)
Net Carrying Value	7,769		7,769		12,908
Trade name [Member]
Components of Intangible Assets [Abstract]
Gross Carrying Value	14,629		14,629		14,629
Accumulated Amortization	(11,330)		(11,330)		(10,416)
Net Carrying Value	3,299		3,299		4,213
Non-compete agreement [Member]
Components of Intangible Assets [Abstract]
Gross Carrying Value	1,687		1,687		1,337
Accumulated Amortization	(1,378)		(1,378)		(1,184)
Net Carrying Value	$ 309		$ 309		$ 153