Commitments, Guarantees and Contingencies - Summary of Commitments, Guarantees and Contingencies (Details) $ in Millions	Sep. 30, 2015 USD ($)
Standby letters of credit
Loss Contingencies [Line Items]
Maximum amount of possible loss contingency	$ 11.8
Bonds related to real estate and construction
Loss Contingencies [Line Items]
Maximum amount of possible loss contingency	$ 419.0	[1]

[1] Represents bonds related to construction and real estate activities in Hawaii, and include construction bonds issued by third party sureties (bid, performance, and payment bonds) and commercial bonds issued by third party sureties (permit, subdivision, license, and notary bonds). In the event the bonds are drawn upon, the Company would be obligated to reimburse the surety that issued the bond. None of the bonds have been drawn upon to date, and the Company believes it is unlikely that any of these bonds will be drawn upon.