Parent Company - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 1,034,644	$ 1,052,058	$ 2,650,195	$ 1,261,453
Other assets	355,258	362,775
Total assets	20,549,461	19,661,829	19,352,681
Liabilities and Stockholders' Equity
Retirement benefits payable	134,218	132,904
Other liabilities	270,536	248,716
Total liabilities	18,016,910	17,185,344
Stockholders' equity
Stockholders' equity	2,532,551	2,476,485	2,736,941	2,675,040
Total liabilities and stockholders' equity	20,549,461	19,661,829
Parent Company
Assets
Cash and cash equivalents	14,337	5,994	$ 10,000	$ 10,000
Investment in FHB	2,522,624	2,440,596
Other assets	23,912	50,831
Total assets	2,560,873	2,497,421
Liabilities and Stockholders' Equity
Retirement benefits payable	780	736
Other liabilities	27,542	20,200
Total liabilities	28,322	20,936
Stockholders' equity
Stockholders' equity	2,532,551	2,476,485
Total liabilities and stockholders' equity	$ 2,560,873	$ 2,497,421