Derivatives and Risk Management Activities (Details 3) In Millions, unless otherwise specified	Sep. 30, 2013 USD ($)	Sep. 30, 2013 Foreign exchange contracts USD ($)	Sep. 30, 2013 Foreign exchange contracts CAD	Sep. 30, 2013 Foreign exchange forward contracts maturing in 2013 USD ($)	Sep. 30, 2013 Foreign exchange forward contracts maturing in 2013 CAD	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.03 maturing in 2013 USD ($)	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.03 maturing in 2013 CAD	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.03 maturing in 2014 USD ($)	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.03 maturing in 2014 CAD	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.04 maturing in 2015 USD ($)	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.04 maturing in 2015 CAD	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.03 USD ($)	Sep. 30, 2013 Foreign exchange forward contracts that exchange CAD for USD at the rate USD 1.00 to CAD 1.03 CAD	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.03 maturing in 2013 USD ($)	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.03 maturing in 2013 CAD	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.04 maturing in 2014 USD ($)	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.04 maturing in 2014 CAD	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.06 maturing in 2015 USD ($)	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.06 maturing in 2015 CAD	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.03 USD ($)	Sep. 30, 2013 Foreign exchange forward contract that exchange USD for CAD at the rate USD 1.00 to CAD 1.03 CAD
Currency Exchange Rate Risk Hedging:
Net deferred gains from currency risk rate hedging included in AOCI	$ 1
Notional amount of outstanding foreign currency forward exchange contracts		$ 2	2	$ 2	2	$ 283	292	$ 104	108	$ 9	9	$ 396	409	$ 281	290	$ 104	108	$ 9	9	$ 394	407
Average exchange rate for outstanding foreign currency forward exchange contracts							1.03		1.03		1.04		1.03		1.03		1.04		1.06		1.03