Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Net Investment	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated other comprehensive loss	Treasury Stock	Total
Balance at Dec. 31, 2015	$ 2,788,200				$ (51,259)		$ 2,736,941
Balance (in shares) at Dec. 31, 2015		139,459,620
Increase (Decrease) in Stockholders' Equity
Net income | Prior to reorganization on April 1, 2016	65,531						65,531
Net income | Subsequent to reorganization on April 1, 2016				$ 164,647			164,647
Net income							230,178
Distributions | Prior to reorganization on April 1, 2016	(363,624)						(363,624)
Distributions | Subsequent to reorganization on April 1, 2016			$ (70,813)				(70,813)
Contributions | Subsequent to reorganization on April 1, 2016			61,992				61,992
Recapitalization of First Hawaiian, Inc. | Subsequent to reorganization on April 1, 2016	$ (2,490,107)	$ 1,395	2,488,712
Cash dividends declared ($0.62, $0.88 and $0.96 per share as of December 31, 2016, 2017 and 2018, respectively) | Subsequent to reorganization on April 1, 2016				(85,797)			(85,797)
Equity-based awards | Subsequent to reorganization on April 1, 2016			4,360				4,360
Equity-based awards (in shares) | Subsequent to reorganization on April 1, 2016		71,034
Other comprehensive loss, net of tax | Subsequent to reorganization on April 1, 2016					(36,752)		(36,752)
Other comprehensive loss, net of tax					(36,752)		(36,752)
Balance at Dec. 31, 2016		$ 1,395	2,484,251	78,850	(88,011)		2,476,485
Balance (in shares) at Dec. 31, 2016		139,530,654
Increase (Decrease) in Stockholders' Equity
Net income				183,682			183,682
Distributions			(2,118)				(2,118)
Cash dividends declared ($0.62, $0.88 and $0.96 per share as of December 31, 2016, 2017 and 2018, respectively)				(122,810)			(122,810)
Common stock issued under Employee Stock Purchase Plan			528				528
Common stock issued under Employee Stock Purchase Plan (in shares)		15,961
Equity-based awards		$ 1	5,982	(545)		$ (282)	5,156
Equity-based awards (in shares)		42,167
Other comprehensive loss, net of tax					(8,372)		(8,372)
Balance at Dec. 31, 2017		$ 1,396	2,488,643	139,177	(96,383)	(282)	$ 2,532,551
Balance (in shares) at Dec. 31, 2017		139,588,782					139,588,782
Increase (Decrease) in Stockholders' Equity
Net income				264,394			$ 264,394
Cash dividends declared ($0.62, $0.88 and $0.96 per share as of December 31, 2016, 2017 and 2018, respectively)				(131,036)			(131,036)
Common stock issued under Employee Stock Purchase Plan			342				342
Common stock issued under Employee Stock Purchase Plan (in shares)		12,341
Equity-based awards		$ 1	6,868	(684)		(53)	6,132
Equity-based awards (in shares)		43,049
Common stock repurchased						(131,800)	(131,800)
Common stock repurchased (in shares)		(4,769,870)
Other comprehensive loss, net of tax					(15,744)		(15,744)
Balance at Dec. 31, 2018		$ 1,397	$ 2,495,853	291,919	(132,195)	$ (132,135)	$ 2,524,839
Balance (in shares) at Dec. 31, 2018		134,874,302					134,874,302
Increase (Decrease) in Stockholders' Equity
Adoption of Accounting Standards Update No. 2018-02				$ 20,068	$ (20,068)