Consolidated Statement of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred taxes on unrealized gain (loss), other, tax effect	$ 7	$ 3	$ 1
Deferred taxes on postretirement	15	(11)	0
Fuel derivatives
Deferred taxes on unrealized gain (loss) on derivatives, tax effect	31	74	42
Interest rate derivatives
Deferred taxes on unrealized gain (loss) on derivatives, tax effect	$ 19	$ 0	$ (20)