Fair Value Measurements (Narrative) (Details) (USD $)				12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 TripIt	Sep. 30, 2012 Short-term Investments	Sep. 30, 2012 Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
High range of financial instrument maturities				1	90
Low range of financial instruments maturities				90
Guaranteed Market Value of Consideration Issued, Per Share			$ 100.90
Fair Value Assumptions, Expected Volatility Rate			42.00%
Convertible Notes Payable	$ 251,607,000	$ 239,461,000
Convertible Debt, Fair Value Disclosures	$ 438,000,000	$ 291,300,000