Credit Facilities and Indebtedness (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended		12 Months Ended		12 Months Ended				12 Months Ended
	May 31, 2007	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2010 5.5% Bonds [Member]	Sep. 30, 2013 5.5% Bonds [Member]	Jun. 08, 2010 5.5% Bonds [Member]	Jun. 30, 2009 7.5% Bonds [Member]	Sep. 30, 2013 7.5% Bonds [Member]	Jun. 15, 2009 7.5% Bonds [Member]	May 11, 2009 Note Warrant [Member]	Sep. 30, 2013 Note Warrant [Member]	May 11, 2009 3.25% Convertible Notes [Member]	Sep. 30, 2013 3.25% Convertible Notes [Member]	May 31, 2009 3.25% Convertible Notes [Member]	Sep. 30, 2013 5.35% [Member]	Sep. 30, 2013 Letters of Credit [Member]	Sep. 30, 2013 Domestic Credit Facility [Member] Interest Coverage Ratio [Member]	Sep. 30, 2013 Domestic Credit Facility [Member] Net Funded Debt Leverage Ratio [Member]	Sep. 30, 2013 Domestic Credit Facility [Member]	Apr. 23, 2013 Domestic Credit Facility [Member]	Sep. 30, 2013 Domestic Credit Facility [Member] Note Hedges [Member]	Sep. 30, 2013 Domestic Credit Facility [Member] Note Warrant [Member]	Apr. 23, 2013 Swing Line Borrowing [Member]
Line of Credit Facility, Maximum Borrowing Capacity																				$ 1,000.0	$ 750.0
Line of Credit Facility, Remaining Borrowing Capacity																	28.0			972.0	50.0			50.0
Term extension prior to maturity, maximum																				60 days
Potential Increase In Credit Facility																				250.0
Line of Credit Facility, Interest Rate Description																				The new facility interest rates and facility fees are based on our public debt ratings or our net funded debt to EBITDA ratio, whichever is more favorable to IGT. Net funded debt is defined as debt minus any unrestricted cash and investments in excess of $150.0 million. At the initial pricing level of Baa2/BBB, the interest rate was LIBOR plus 100 bps and the facility fee was 17.5 bps.
Debt issuance costs capitalized																				3.3
Deferred Offering Costs							3.0			4.0			27.5			4.0				8.2
Debt Instrument, Covenant Description																		3.0	3.5
NotesAggregatePrincipalAmount													850.0
Proceeds from Issuance of Private Placement													822.5
Debt Instrument, Convertible, Terms of Conversion Feature														Each $1,000 Note is initially convertible into 50.3630 shares of IGT Common Stock, representing a conversion price of $19.86 per share.The Notes are convertible under any of the following circumstances: · during any fiscal quarter ending after September 30, 2009 (and only during such fiscal quarter), if the closing price of our common stock for at least 20 trading days in the last 30 trading day period of the immediately preceding fiscal quarter is more than 130% of the conversion price on the last trading day of the preceding fiscal quarter · if specified corporate transactions occur as described further in the indenture · at any time on or after February 1, 2014 until the close of business on the second scheduled trading day immediately preceding May 1, 2014
Debt Instrument, Convertible, Conversion Price (in Dollars per share)															$ 19.86					$ 19.86
Debt Instrument, Convertible, Carrying Amount of Equity Component															99.7
Debt Instrument, Interest Rate, Effective Percentage (in hundredths)															8.70%	5.18%
Initial Note Conversion Price (in Dollars per share)													$ 30.14		$ 30.14
Share Price Increase Percentage													10.00%
Conversion of Stock, Shares Issued (in Shares)													3.9
Derivative, Cost of Hedge Net of Cash Received																						177.3
Deferred Tax Assets, Hedging Transactions																						65.5
Derivative, Cash Received on Hedge											66.8												66.8
Common Shares Covered By Hedge (in Shares)											42.6												42.6
Derivative, Price Risk Option Strike Price (in Dollars per Item)		$ 19.86																		$ 19.86
Maximum Shares Delivered (in Shares)												72.6
Aggregate Principal Amount						300.0			500.0							500.0
Stated interest rate (in hundredths)						5.50%			7.50%					3.25%		5.35%
Proceeds from Issuance of Long-term Debt		617.9	280.0	95.0	295.7			493.3								493.9
Debt Instrument, Unamortized Discount							1.3			2.7						2.1
Maturity date	May 31, 2015					Jun. 15, 2020			Jun. 15, 2019					May 01, 2014
Debt redemption rate (in hundredths)						100.00%			100.00%							100.00%
Effective portion gain (loss) recorded in AOCI		$ 12.6
Amortization period																10 years