Intangible Assets (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			3 Months Ended	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2011 ADP, Inc. [Member] Y	Sep. 30, 2012 ADP, Inc. [Member]
Finite-Lived Intangible Assets [Line Items]
Payments for aquisitions net of cash aquired	$ 68,266	$ 42,424	$ 3,623		$ 67,300
Standard Length of Customer Contract				1 year
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life				9
Amount of Historical Data used to determine useful life (in years)				12 years
Amortization of intangible assets	$ 18,239	$ 10,131	$ 7,224