Cash flows (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Supplemental disclosures of cash flow information
Interest paid to non-affiliates	$ 22	$ 23
Income taxes paid/(refunded)		(30)
Supplemental disclosures of noncash activities
Common stock dividends reinvested in HEI common stock	6	6
Increases in common stock issued under director and officer compensatory plans	2	4
Real estate acquired in settlement of loans	$ 2	$ 3