Schedule I - Condensed Financial Information of Parent Company (Statements of Cash Flows) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
OPERATING ACTIVITIES
Net income	$ (212)	$ 285	$ 257
Loss (income) from discontinued operations, net of income taxes	322	(67)	(35)
Adjustments to reconcile net income to net cash from operating activities:
Deferred income taxes	458	312	178
Changes in:
Other assets and liabilities	9	16	43
Net Cash From Operating Activities	497	592	686
FINANCING ACTIVITIES
Dividends paid on common stock	(270)	(248)	(244)
Common stock issued for the Direct Stock Purchase and Dividend Reinvestment Plan and employee-related compensation	50	51	47
Issuances of common stock	324
Issuance of term loan	250	200
Repayments of term loans	450
Costs of issuances	(23)	(9)	(10)
Net Cash (Used By) From Financing Activities	(88)	293	149
Net (Decrease) Increase In Cash and Cash Equivalents	(2)	(84)	88
Cash and Cash Equivalents at Beginning of Year	25	109	21
CASH AND CASH EQUIVALENTS AT END OF YEAR	23	25	109
Parent Company [Member]
OPERATING ACTIVITIES
Net income	(212)	285	257
Loss (income) from discontinued operations, net of income taxes	322	(67)	(35)
Adjustments to reconcile net income to net cash from operating activities:
Distributions from related parties less than earnings	(127)	(52)	(169)
Deferred income taxes	(7)	(31)	(16)
Changes in:
Prepaid and other	2	(23)	23
Accounts payable	6	6	2
Interest and taxes	(141)	39	42
Other assets and liabilities	3	4	11
Net Cash From Operating Activities	(154)	161	115
FINANCING ACTIVITIES
Dividends paid on common stock	(270)	(248)	(244)
Common stock issued for the Direct Stock Purchase and Dividend Reinvestment Plan and employee-related compensation	50	51	47
Issuances of common stock	324
Capital distribution to subsidiaries, net	(250)	(110)	(20)
Decrease in notes receivable from associated companies		154
Increase in notes payable due to associated companies	491
(Repayments) issuances of short-term debt, net	(240)	(201)	235
Issuance of term loan	250	200
Repayments of term loans	(450)
Costs of issuances	(13)	(2)	(7)
Net Cash (Used By) From Financing Activities	(108)	(156)	11
Net (Decrease) Increase In Cash and Cash Equivalents	(262)	5	126
Cash and Cash Equivalents at Beginning of Year	262	257	131
CASH AND CASH EQUIVALENTS AT END OF YEAR		$ 262	$ 257