Acquisitions (Narrative) (Details) (USD $)	1 Months Ended	3 Months Ended	9 Months Ended			9 Months Ended		9 Months Ended		9 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended					1 Months Ended		3 Months Ended	9 Months Ended			1 Months Ended	3 Months Ended	9 Months Ended				9 Months Ended		9 Months Ended	3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended
	Oct. 31, 2011 ShareFile [Member]	Sep. 30, 2011 ShareFile [Member]	Sep. 30, 2011 ShareFile [Member]	Oct. 31, 2011 ShareFile [Member] Product Related Technologies [Member]	Oct. 31, 2011 ShareFile [Member] Other Intangible Assets [Member]	Sep. 30, 2012 Podio [Member]	Apr. 30, 2012 Podio [Member]	Sep. 30, 2012 Podio [Member] Core And Product Technologies [Member]	Sep. 30, 2012 2012 Acquisition [Member]	Sep. 30, 2012 2012 Acquisition [Member] Core And Product Technologies [Member]	Mar. 31, 2012 Other 2012 Acquisitions, Private Company [Member]	Nov. 30, 2011 App Dna [Member]	Sep. 30, 2011 App Dna [Member]	Sep. 30, 2011 App Dna [Member]	Nov. 30, 2011 App Dna [Member] Product Related Technologies [Member]	Nov. 30, 2011 App Dna [Member] Other Intangible Assets [Member]	Sep. 30, 2011 Netviewer AG [Member]	Sep. 30, 2012 Netviewer AG [Member]	Sep. 30, 2011 Netviewer AG [Member]	Feb. 28, 2011 Netviewer AG [Member]	Sep. 30, 2012 Netviewer AG [Member] Core And Product Technologies [Member]	Sep. 30, 2012 Netviewer AG [Member] Other Intangible Assets [Member]	May 31, 2011 Kaviza, Inc. [Member]	Jul. 31, 2011 Cloud.Com [Member]	Sep. 30, 2011 Cloud.Com [Member]	Sep. 30, 2011 Cloud.Com [Member]	Jul. 31, 2011 Cloud.Com [Member] Product Related Technologies [Member]	Jul. 31, 2011 Cloud.Com [Member] Other Intangible Assets [Member]	Aug. 31, 2011 Ringcube [Member]	Sep. 30, 2011 Ringcube [Member]	Sep. 30, 2011 Ringcube [Member]	Aug. 31, 2011 Ringcube [Member] Product Related Technologies [Member]	Aug. 31, 2011 Ringcube [Member] Other Intangible Assets [Member]	Sep. 30, 2012 Other Acquisition [Member]	Sep. 30, 2012 Bytemobile [Member]	Jul. 31, 2012 Bytemobile [Member]	Sep. 30, 2012 Bytemobile [Member] Core And Product Technologies [Member]	Mar. 31, 2012 Q1 Other 2012 Acquisitions, Private Company [Member]	Sep. 30, 2012 Q1 Other 2012 Acquisitions, Private Company [Member]	Sep. 30, 2012 Q1 Other 2012 Acqusitions, Two Private Companies [Member]	Jun. 30, 2012 Q2 Other 2012 Acqusitions, Two Private Companies [Member]	Sep. 30, 2012 Q2 Other 2012 Acqusitions, Two Private Companies [Member]	Sep. 30, 2012 Q3 Other 2012 Acqusitions, Two Private Companies [Member]
Total consideration in business acquisitions	$ 54,000,000						$ 43,600,000					$ 91,300,000								$ 107,500,000				$ 158,800,000					$ 32,200,000					$ 10,500,000		$ 400,700,000		$ 24,600,000			$ 15,400,000		$ 5,300,000
Cash acquired in business combination	1,700,000						1,700,000					3,200,000								6,300,000				5,600,000					500,000							5,600,000		600,000			200,000
Transaction costs	700,000					0	500,000				500,000	1,300,000								3,100,000				2,900,000					600,000						0	2,100,000				0	400,000	0	200,000
Transaction costs expensed in period		400,000	400,000			500,000							400,000	400,000			100,000		900,000						2,300,000	2,900,000				500,000	600,000				2,100,000				400,000	400,000		400,000	200,000
Assets acquired						52,042,000			76,665,000																										565,553,000
Acquired finite-lived intangible asset, amount	28,200,000			16,000,000	12,200,000			20,700,000		26,112,000		44,800,000			36,700,000	8,100,000		28,800,000			3,200,000	25,600,000		89,000,000			58,000,000	31,000,000	30,600,000			26,000,000	4,600,000				98,000,000
Weighted average life (in years)								5 years		4 years 7 months 6 days																											4 years 10 months 24 days
Goodwill	49,400,000					25,503,000			44,794,000			58,200,000						98,700,000						100,600,000					14,400,000						202,113,000
Additional investment in the consolidated subsidiary																							$ 17,200,000
Stock units converted and assumed	180,697					127,668						114,487						99,100					88,687	288,742					58,439									13,481			66,459		13,487
Stock options converted and assumed	390,775																						33,301	183,780														12,017
Equity interest in subsidiary																							100.00%