Fair value measurements - (Details) - HECO (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Hawaiian Electric Company, Inc. and Subsidiaries \| Carrying or notional amount
Financial assets
Cash and cash equivalents, excluding money market funds	$ 13,869	$ 122,936
Financial liabilities
Long-term debt, net, including amounts due within one year	1,058,038	1,057,942
Off-balance sheet items
HECO-obligated preferred securities of trust subsidiary	50,000	50,000
Carrying or notional amount
Financial assets
Cash and cash equivalents, excluding money market funds	283,473	329,553
Financial liabilities
Long-term debt, net, including amounts due within one year	1,340,038	1,364,942
Hawaiian Electric Company, Inc. and Subsidiaries \| Estimated fair value
Financial assets
Cash and cash equivalents, excluding money market funds	13,869	122,936
Financial liabilities
Long-term debt, net, including amounts due within one year	1,033,222	1,020,550
Off-balance sheet items
HECO-obligated preferred securities of trust subsidiary	51,960	52,500
Estimated fair value
Financial assets
Cash and cash equivalents, excluding money market funds	283,473	329,553
Financial liabilities
Long-term debt, net, including amounts due within one year	$ 1,342,518	$ 1,345,770

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

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