Consolidated Balance Sheets (Parenthetical) - HECO (USD $)	Mar. 31, 2012	Dec. 31, 2011
Common stock, authorized shares	200,000,000	200,000,000
Common stock, outstanding shares	96,541,143	96,038,328
Hawaiian Electric Company, Inc. and Subsidiaries
Common stock, par value (in dollars per share)	6.67	6.67
Common stock, authorized shares	50,000,000	50,000,000
Common stock, outstanding shares	14,233,723	14,233,723