Goodwill and Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2012 Software Products Segment [Member]	Sep. 30, 2011 Software Products Segment [Member]	Mar. 31, 2012 Services Segment [Member]	Sep. 30, 2011 Services Segment [Member]
Goodwill and acquired intangible assets		$ 792.9	$ 806.0	$ 28.8	$ 29.4
Estimated aggregate future amortization expense for intangible assets, Current Year	18.1
Estimated aggregate future amortization expense for intangible assets, Year One	36.4
Estimated aggregate future amortization expense for intangible assets, Year Two	34.3
Estimated aggregate future amortization expense for intangible assets, Year Three	30.8
Estimated aggregate future amortization expense for intangible assets, Year Four	23.2
Estimated aggregate future amortization expense for intangible assets, Year Five	19.6
Estimated aggregate future amortization expense for intangible assets, After Year Five	$ 42.6