Bank segment (HEI only) - Balance Sheets Data (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents, December 31	$ 341,421		$ 196,813	$ 169,208
Investment securities
Available-for-sale, at fair value	1,970,417		1,232,826
Held-to-maturity, at amortized cost (fair value of $229,963 and $143,467 at December 31, 2020 and 2019, respectively)	226,947		139,451
Stock in Federal Home Loan Bank, at cost	8,680		8,434
Loans held for investment	5,345,226		5,120,664	4,843,634
Allowance for credit losses	(101,201)		(53,355)	(52,119)	$ (53,637)
Total financing receivables	5,232,642	$ 5,067,821	5,067,821
Loans held for sale, at lower of cost or fair value	28,275		12,286
Other	629,149		649,885
Goodwill	82,190		82,190
Total assets	15,004,007	13,745,251	13,745,251	13,104,051
LIABILITIES AND SHAREHOLDERS’ EQUITY
Other	618,438	583,545	583,545
Total liabilities	12,632,212	11,430,698	11,430,698
Commitments and contingencies
Retained earnings	660,398	622,042	622,042
Net unrealized gains on securities	19,986		2,481
Accumulated other comprehensive income (loss), net of taxes	(1,264)		(20,039)
Total shareholders’ equity	2,337,502	2,280,260	2,280,260	$ 2,162,280	$ 2,097,386
Total capitalization and liabilities	15,004,007	13,745,251	13,745,251
Other assets
Premises and equipment, net	5,265,735		5,109,628
Total other assets	629,149		649,885
Other liabilities
Total other liabilities	618,438	$ 583,545	583,545
Held-to-maturity investment securities	229,963		143,467
American Savings Bank (ASB)
Assets
Cash and due from banks	178,422		129,770
Interest-bearing deposits	114,304		48,628
Cash and cash equivalents, December 31	292,726		178,398
Investment securities
Available-for-sale, at fair value	1,970,417		1,232,826
Held-to-maturity, at amortized cost (fair value of $229,963 and $143,467 at December 31, 2020 and 2019, respectively)	226,947		139,451
Stock in Federal Home Loan Bank, at cost	8,680		8,434
Loans held for investment	5,333,843		5,121,176
Allowance for credit losses	(101,201)		(53,355)
Total financing receivables	5,232,642		5,067,821
Loans held for sale, at lower of cost or fair value	28,275		12,286
Other	554,656		511,611
Goodwill	82,190		82,190
Total assets	8,396,533		7,233,017
LIABILITIES AND SHAREHOLDERS’ EQUITY
Deposit liabilities–noninterest-bearing	2,598,500		1,909,682
Deposit liabilities–interest-bearing	4,788,457		4,362,220
Other borrowings	89,670		115,110
Other	183,731		146,954
Total liabilities	7,660,358		6,533,966
Commitments and contingencies
Common stock	1		1
Additional paid in capital	351,758		349,453
Retained earnings	369,470		358,259
Net unrealized gains on securities	19,986		2,481
Retirement benefit plans	(5,040)		(11,143)
Accumulated other comprehensive income (loss), net of taxes	14,946		(8,662)
Total shareholders’ equity	736,175		699,051
Total capitalization and liabilities	8,396,533		7,233,017
Other assets
Bank-owned life insurance	163,265		157,465
Premises and equipment, net	206,134		204,449
Accrued interest receivable	24,616		19,365
Mortgage servicing rights	10,020		9,101
Low-income housing investments	83,435		66,302
Other	67,186		54,929
Total other assets	554,656		511,611
Other liabilities
Accrued expenses	62,694		45,822
Federal and state income taxes payable	6,582		14,996
Cashier’s checks	38,011		23,647
Advance payments by borrowers	10,207		10,486
Other	66,237		52,003
Total other liabilities	183,731		146,954
Held-to-maturity investment securities	$ 229,963		$ 143,467