Hedging Hedge Portfolio Table (Details) In Millions, unless otherwise specified	Sep. 30, 2012 Purchased euro put options settling in 2012 [Member] USD ($)	Sep. 30, 2012 Purchased euro put options settling in 2012 [Member] EUR (€)	Sep. 30, 2012 Sold euro call options settling in 2012 [Member] USD ($)	Sep. 30, 2012 Sold euro call options settling in 2012 [Member] EUR (€)	Sep. 30, 2012 Average rate forward contracts settling in 2012 [Domain] USD ($)	Sep. 30, 2012 Average rate forward contracts settling in 2012 [Domain] EUR (€)	Sep. 30, 2012 Purchased euro put options settling in 2013 [Member] USD ($)	Sep. 30, 2012 Purchased euro put options settling in 2013 [Member] EUR (€)	Sep. 30, 2012 Sold euro call options settling in 2013 [Member] USD ($)	Sep. 30, 2012 Sold euro call options settling in 2013 [Member] EUR (€)	Sep. 30, 2012 Average rate forward contracts settling in 2013 [Domain] [Domain] USD ($)	Sep. 30, 2012 Average rate forward contracts settling in 2013 [Domain] [Domain] EUR (€)	Sep. 30, 2012 2012 [Member] Mg		Sep. 30, 2012 2013 [Member] Mg		Sep. 30, 2012 2014 [Member] Mg		Sep. 30, 2012 2015 [Member] Mg		Sep. 30, 2012 30 day euro forward contract [Member] USD ($)	Sep. 30, 2012 30 day euro forward contract [Member] EUR (€)
Derivative [Line Items]
Notional amount of currency derivatives designated cash flow hedges		€ 51		€ 51		€ 35		€ 212		€ 212		€ 148
Currency derivatives designated cash flow hedges contract average of price (in USD per euro)	1.23		1.31		1.23		1.20		1.28		1.23
Notional amount of fuel derivatives designated cash flow hedges													19,176	[1]	76,701	[1]	108,416	[1]	74,640	[1]
Fuel derivatives designated cash flow hedges contract average rate (in USD per mt)													463	[1]	497	[1]	587	[1]	564	[1]
Notional amount of foreign currency derivative instruments not designated as hedging instruments																						€ 65
Foreign currency derivative instruments not designated as hedging instruments average forward exchange rate																					1.29

[1] As described in the paragraph above, new cash flow hedge relationships were established for certain bunker fuel forward contracts in 2011. These changes resulted in hedge rates for accounting purposes that are different from those in the hedge contract terms.