Parent Company - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 1,003,637	$ 1,034,644	$ 1,052,058	$ 2,650,195
Other assets	446,404	355,258
Total assets	20,695,678	20,549,461	19,661,829
Liabilities and Stockholders' Equity
Retirement benefits payable	127,909	134,218
Other liabilities	292,836	270,536
Total liabilities	18,170,839	18,016,910
Stockholders' equity
Stockholders' equity	2,524,839	2,532,551	2,476,485	2,736,941
Total liabilities and stockholders' equity	20,695,678	20,549,461
Parent Company
Assets
Cash and cash equivalents	5,647	14,337	$ 5,994	$ 10,000
Investment in FHB	2,521,347	2,522,624
Other assets	19,358	23,912
Total assets	2,546,352	2,560,873
Liabilities and Stockholders' Equity
Retirement benefits payable	509	780
Other liabilities	21,004	27,542
Total liabilities	21,513	28,322
Stockholders' equity
Stockholders' equity	2,524,839	2,532,551
Total liabilities and stockholders' equity	$ 2,546,352	$ 2,560,873