Business Acquisitions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended					0 Months Ended	1 Months Ended		12 Months Ended	1 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012 Maximum Earnout Payments [Member] Double Down Interactive, LLC [Member]	Sep. 30, 2012 Maximum Employee Retention Payments [Member] Double Down Interactive, LLC [Member]	Jan. 20, 2012 Double Down Interactive, LLC [Member]	Apr. 30, 2012 Double Down Interactive, LLC [Member]	Mar. 31, 2012 Double Down Interactive, LLC [Member]	Sep. 30, 2012 Double Down Interactive, LLC [Member]	Feb. 28, 2012 BringIt, Inc. [Member]	Jun. 30, 2011 Entraction Holding AB [Member]	May 31, 2014 IGT_Strategy9 [Member]
Business Acquisition, Percentage of Voting Interests Acquired (in hundredths)						100.00%
Business Acquisition, Cost of Acquired Entity, Purchase Price						$ 250.9			$ 339.8			$ 2.4
Business Acquisition, Cost of Acquired Entity, Cash Paid							0.9	225.0		8.1	110.7	1.5
Business Combination, Indemnification Assets, Amount as of Acquisition Date						25.0
Business Acquisition, Contingent Consideration, Potential Cash Payment				165.0	85.0	500.9				2.0		2.8
Business Acquisition, Contingent Consideration, at Fair Value						88.9
Risk Adjusted Discount Rate (in hundredths)						19.00%
Business Acquisition, Purchase Price Allocation, Net Tangible Assets						7.2					2.9
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets						109.2				0.8	17.7	1.9
Business Acquisition, Purchase Price Allocation, Goodwill Amount						226.1				6.7	90.1	0.5
Business Acquisition, Purchase Price Allocation, Liabilities Assumed						2.7						0.9
Business Combination, Acquisition Related Costs	$ 19.6	$ 73.9	$ 69.1						$ 5.6
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage (in hundredths)											100.00%