Goodwill and Acquired Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013 segments	Sep. 30, 2014
Number of reportable segments	2
Estimated aggregate future amortization expense for intangible assets, 2014		$ 54.7
Estimated aggregate future amortization expense for intangible assets, 2015		51.2
Estimated aggregate future amortization expense for intangible assets, 2016		48.6
Estimated aggregate future amortization expense for intangible assets, 2017		46.3
Estimated aggregate future amortization expense for intangible assets, 2018		36.7
Estimated aggregate future amortization expense for intangible assets, thereafter		99.4
Software Products [Member]
Goodwill and acquired intangible assets	979.3	1,283.0
Services [Member]
Goodwill and acquired intangible assets	$ 62.9	$ 66.4