Parent Company - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net income	$ 265,735	$ 185,754	$ 284,392
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	14,120	(19,396)	17,060
Stock-based compensation	13,106	10,028	7,826
Change in assets and liabilities:
Net (increase) decrease in other assets	(8,211)	(17,880)	(20,923)
Net increase (decrease) in other liabilities	110,613	(114,613)	(76,303)
Net cash provided by operating activities	417,125	209,506	296,504
Cash flows from financing activities
Dividends paid	(134,133)	(135,099)	(138,246)
Stock tendered for payment of withholding taxes	(3,108)	(1,749)	(1,764)
Proceeds from employee stock purchase plan	547	312
Common stock repurchased	(75,000)	(5,000)	(136,242)
Net cash provided by (used in) financing activities	2,176,719	2,241,184	(981,336)
Net increase (decrease) in cash and cash equivalents	217,525	346,927	(309,620)
Cash and cash equivalents at beginning of year	1,040,944	694,017	1,003,637
Cash and cash equivalents at end of year	1,258,469	1,040,944	694,017
First Hawaiian, Inc.
Adjustments to reconcile net income to net cash provided by operating activities:
(Equity in undistributed income) excess distributions of FHB	(58,135)	(49,580)	10,620
Deferred income taxes	36	5	85
Stock-based compensation	492	713	84
Change in assets and liabilities:
Net (increase) decrease in other assets	242	(1,451)	5,318
Net increase (decrease) in other liabilities	50	(294)	(5,439)
Net cash provided by operating activities	208,420	135,147	295,060
Cash flows from financing activities
Dividends paid	(134,133)	(135,099)	(138,246)
Stock tendered for payment of withholding taxes	(3,108)	(1,749)	(1,764)
Proceeds from employee stock purchase plan	547	312
Common stock repurchased	(75,000)	(5,000)	(136,242)
Net cash provided by (used in) financing activities	(211,694)	(141,536)	(276,252)
Net increase (decrease) in cash and cash equivalents	(3,274)	(6,389)	18,808
Cash and cash equivalents at beginning of year	18,066	24,455	5,647
Cash and cash equivalents at end of year	$ 14,792	$ 18,066	$ 24,455