Cash flows (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Supplemental disclosures of cash flow information
Interest paid to non-affiliates	$ 97,000,000	$ 95,000,000	$ 106,000,000
Income taxes paid/(refunded)	(22,000,000)	6,000,000	21,000,000
Supplemental disclosures of noncash activities
Common stock dividends reinvested in HEI common stock	12,000,000	23,000,000	17,000,000
Increases in common stock issued under director and officer compensatory plans	8,000,000	4,000,000	2,000,000
Electric utility property plant and equipment
AFUDC-equity	5,964,000	6,016,000	12,222,000
Estimated fair value of noncash contributions in aid of construction	7,000,000	7,000,000	12,000,000
Unpaid invoices and other	45,000,000	21,000,000	16,000,000
Loans transferred from held for investment to held for sale	6,000,000		10,000,000
Real estate acquired in settlement of loans	$ 12,000,000	$ 7,000,000	$ 5,000,000