Equity (Narrative) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Feb. 12, 2014
Equity Contract [Member]
Equity Distribution Agreement, shares issued	5	10
Equity distribution agreement amount			$ 500
Fees and commissions	2	4
Stock Issued During Period Value Under Equity Distribution Agreement	206	429
401K Plan, DRSPP, and Shared Based Compensation Plans [Member]
Stock issued during period for stock options exercised and under 401(K) plan and DRSPP, shares		4
Stock Issued During Period Value Stock Options Exercised		$ 160