Business Acquisition (Narrative) (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified				3 Months Ended	9 Months Ended
	Jun. 30, 2011	Jan. 24, 2011	Sep. 30, 2010	Jun. 30, 2011 TripIt, Inc. [Member]	Jun. 30, 2011 TripIt, Inc. [Member]	Jan. 24, 2011 TripIt, Inc. [Member]	Jun. 30, 2011 TripIt, Inc. [Member] Minimum [Member]	Jun. 30, 2011 TripIt, Inc. [Member] Maximum [Member]	Jun. 30, 2011 TripIt, Inc. [Member] Cost Attributed to Precombination Service Period [Member]	Jun. 30, 2011 TripIt, Inc. [Member] Top-Up Payment Subject to Continued Employment [Member]	Jan. 24, 2011 TripIt, Inc. [Member] Top-Up Payment Subject to Continued Employment [Member]	Jan. 24, 2011 TripIt, Inc. [Member] Top-Up Payment Recorded as Part of Purchase Consideration [Member]	Jun. 30, 2011 TripIt, Inc. [Member] Top-Up payment Due to Other Former Shareholders [Member]
Cash paid for acquisition						$ 24,700,000
Number of share issued						814
Value of shares issued						41,200,000
Shares held in escrow				217	217
Contingent consideration, fair value	31,100,000	28,900,000		31,100,000	31,100,000	28,900,000					11,500,000	17,400,000
Replacement award attributable to precombination service period									3,600,000
Fair Value of Replacement Awards				9,900,000	9,900,000
Transaction costs, expensed during period				0	1,900,000
Additional cash consideration	38,300,000							38,300,000
Top-up payment							0
Additional cash consideration payment applicability term (months)				30	30
Guaranteed market value of consideration issued				82,100,000	82,100,000
Guaranteed market value of consideration issued, per share				$ 100.9	$ 100.9
Acquisition-related contingent consideration	24,110,000
Acquisition-related liabilities	2,888,000			24,100,000	24,100,000					5,300,000			18,800,000
Deferred compensation costs related to merger				$ 7,000,000	$ 7,000,000