SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities
Net income	$ 140,120,000	$ 115,425,000	$ 84,901,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation of property, plant and equipment	148,152,000	154,523,000	151,282,000
Changes in deferred income taxes	79,444,000	97,791,000	12,787,000
Changes in excess tax benefits from share-based payment arrangements	35,000	45,000	310,000
Changes in assets and liabilities
Increase (decrease) in accounts, interest and dividends payable	(34,480,000)	22,410,000	(12,472,000)
Changes in other assets and liabilities	(26,094,000)	36,270,000	(39,491,000)
Contributions to defined benefit pension and other postretirement benefit plans	(74,961,000)	(31,792,000)	(25,354,000)
Net cash provided by operating activities	250,366,000	340,717,000	268,586,000
Cash flows from investing activities
Capital expenditures	(235,116,000)	(182,125,000)	(288,879,000)
Other	(2,974,000)	5,092,000	1,199,000
Net cash provided by (used in) investing activities	(326,787,000)	(278,734,000)	457,508,000
Cash flows from financing activities
Net increase (decrease) in short-term borrowings with original maturities of three months or less	43,898,000	(17,066,000)	41,989,000
Proceeds from issuance of long-term debt	125,000,000		153,186,000
Changes in excess tax benefits from share-based payment arrangements	(35,000)	(45,000)	(310,000)
Net proceeds from issuance of common stock	15,979,000	22,706,000	15,329,000
Common stock dividends	(106,812,000)	(93,034,000)	(96,843,000)
Net cash provided by (used in) financing activities	16,035,000	(235,254,000)	(405,607,000)
Net increase (decrease) in cash and cash equivalents	(60,386,000)	(173,271,000)	320,487,000
Cash and cash equivalents, January 1	330,651,000	503,922,000	183,435,000
Cash and cash equivalents, December 31	270,265,000	330,651,000	503,922,000
Common stock dividends reinvested by shareholders	21,217,000	37,296,000	27,701,000
Common Stock Including Additional Paid in Capital [Member]
Cash flows from financing activities
Common stock dividends reinvested by shareholders	21,217,000	37,296,000	27,701,000
Hawaiian Electric Industries, Inc.
Cash flows from operating activities
Net income	138,230,000	113,535,000	83,011,000
Adjustments to reconcile net income to net cash provided by operating activities
Equity in net income	(158,722,000)	(134,470,000)	(100,896,000)
Common stock dividends/distributions received from subsidiaries	128,558,000	110,769,000	105,128,000
Depreciation of property, plant and equipment	227,000	320,000	409,000
Other amortization	981,000	625,000	373,000
Changes in deferred income taxes	276,000	(1,432,000)	(78,000)
Changes in excess tax benefits from share-based payment arrangements	35,000	45,000	310,000
Changes in assets and liabilities
Decrease (increase) in accounts receivable	412,000	(148,000)	213,000
Increase (decrease) in accounts, interest and dividends payable	1,324,000	936,000	165,000
Changes in prepaid and accrued income taxes	3,550,000	(1,897,000)	(2,799,000)
Changes in other assets and liabilities	5,183,000	4,381,000	4,922,000
Contributions to defined benefit pension and other postretirement benefit plans	(1,785,000)	(724,000)	(1,267,000)
Net cash provided by operating activities	118,269,000	91,940,000	89,491,000
Cash flows from investing activities
Net decrease (increase) in notes receivables from subsidiaries			10,464,000
Capital expenditures	(110,000)	(84,000)	(246,000)
Investments in subsidiaries	(40,000,000)	(4,364,000)	(61,969,000)
Other	(4,206,000)
Net cash provided by (used in) investing activities	(44,316,000)	(4,448,000)	(51,751,000)
Cash flows from financing activities
Net increase (decrease) in notes payable to subsidiaries with original maturities of three months or less	(1,757,000)	(1,428,000)	(2,120,000)
Net increase (decrease) in short-term borrowings with original maturities of three months or less	43,897,000	(17,066,000)	41,989,000
Proceeds from issuance of long-term debt	125,000,000
Repayments of short-term borrowings with original maturities greater than three months	(150,000,000)
Changes in excess tax benefits from share-based payment arrangements	(35,000)	(45,000)	(310,000)
Net proceeds from issuance of common stock	15,979,000	22,706,000	15,329,000
Common stock dividends	(106,812,000)	(93,034,000)	(96,843,000)
Net cash provided by (used in) financing activities	(73,728,000)	(88,867,000)	(41,955,000)
Net increase (decrease) in cash and cash equivalents	225,000	(1,375,000)	(4,215,000)
Cash and cash equivalents, January 1	1,540,000	2,915,000	7,130,000
Cash and cash equivalents, December 31	1,765,000	1,540,000	2,915,000
Value of stock converted to equity in noncash transaction	1,300,000	1,100,000	1,300,000
Hawaiian Electric Industries, Inc. | Common Stock Including Additional Paid in Capital [Member]
Cash flows from financing activities
Common stock dividends reinvested by shareholders	$ 12,000,000	$ 23,000,000	$ 17,000,000