Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
ALLOWANCE FOR DOUBTFUL ACCOUNTS
Balance at beginning of year	$ 6,549	$ 12,946	$ 15,048
Charged to income	2,244	1,415	4,269
Recoveries and adjustments	(1,463)	(1,262)	(1,744)
Net additions	781	153	2,525
Less uncollectible accounts written off	(1,636)	(6,550)	(4,627)
Balance at end of year	5,694	6,549	12,946
Alabama Gas Corporation
ALLOWANCE FOR DOUBTFUL ACCOUNTS
Balance at beginning of year	5,700	12,100	14,200
Charged to income	2,243	1,409	4,202
Recoveries and adjustments	(1,469)	(1,263)	(1,745)
Net additions	774	146	2,457
Less uncollectible accounts written off	(1,474)	(6,546)	(4,557)
Balance at end of year	$ 5,000	$ 5,700	$ 12,100