Statements of Consolidated Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net income	$ 31,446	$ 87,754	$ 103,481	$ 210,009
Net change in cash flow hedges:
Natural gas, net of tax (benefit) expense of $(41,598), $14,240, $(3,105) and $6,451 (see Note C)	(64,216)	23,334	(4,714)	10,630
Interest rate, net of tax (benefit) of ($4,966), $0, ($3,165) and $0	(6,606)	29	(4,168)	58
Unrealized loss on available-for-sale securities, net of tax of $1,575 and $2,636		(2,925)		(4,896)
Pension and other post-retirement benefits liability adjustment, net of tax of $92, $281, $214 and $563	489	413	1,436	824
Other comprehensive (loss) income	(70,333)	20,851	(7,446)	6,616
Comprehensive (loss) income	$ (38,887)	$ 108,605	$ 96,035	$ 216,625