Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, plant and equipment, accumulated depreciation	$ 2,587,998	$ 2,553,295
Preferred stock, authorized shares (in shares)	10,000,000	10,000,000
Preferred stock, issued shares (in shares)	0	0
Common stock, authorized shares (in shares)	200,000,000	200,000,000
Common stock, issued shares (in shares)	108,841,157	108,787,807
Common stock, outstanding shares (in shares)	108,841,157	108,787,807
Hawaiian Electric Company, Inc. and Subsidiaries
Nonutility property, plant and equipment, accumulated depreciation	$ 1,252	$ 1,251
Common stock, par value (in dollars per share)	$ 6.67	$ 6.67
Common stock, authorized shares (in shares)	50,000,000	50,000,000
Common stock, outstanding shares (in shares)	16,142,216	16,142,216