Bank segment - Mortgage servicing rights (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Servicing Asset at Amortized Cost [Line Items]
Repurchase reserve				$ 100		$ 100
Valuation Allowance [Roll Forward]
Weighted average discount rate (as a percent)	2.658%
American Savings Bank (ASB)
Servicing Asset at Amortized Cost [Line Items]
Mortgage service fees	$ 800	$ 700
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing asset - beginning balance	9,373
Servicing asset - ending balance	9,294		$ 9,373
American Savings Bank (ASB) | Mortgage Servicing Rights (MSR)
Servicing Asset at Amortized Cost [Line Items]
Gross carrying amount				17,707	$ 17,271
Accumulated amortization				(8,413)	(7,898)
Valuation allowance	0	0	0	0	0	0
Net carrying amount				9,294	9,373	$ 8,857
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing asset - beginning balance	9,373	8,884	8,884
Amount capitalized	436	455
Amortization	(515)	(482)
Other-than-temporary impairment	0	0
Servicing asset - ending balance	9,294	8,857	9,373
Valuation Allowance [Roll Forward]
Valuation allowance, beginning balance	0	0	0
Provision (recovery)	0	0
Other-than-temporary impairment	0	0
Valuation allowance, ending balance	$ 0	0	$ 0
Unpaid principal balance				1,205,197	1,188,380
Weighted average note-rate (as a percent)	3.95%		3.96%
Weighted average discount rate (as a percent)	9.50%		9.40%
Weighted average prepayment speed (as a percent)	8.20%		8.50%
Prepayment rate - 25 points adverse rate change				(556)	(567)
Prepayment rate - 50 points adverse rate change				(1,144)	(1,154)
Discount rate - 25 points adverse rate change				(134)	(128)
Discount rate - 50 points adverse rate change				$ (266)	$ (254)
American Savings Bank (ASB) | Measurement Band A
Valuation Allowance [Roll Forward]
Measurement band percent for risk categorization	0.50%
American Savings Bank (ASB) | Measurement Band B
Valuation Allowance [Roll Forward]
Measurement band percent for risk categorization	1.00%
American Savings Bank (ASB) | Residential loan
Servicing Asset at Amortized Cost [Line Items]
Proceeds from sale of mortgage loans	$ 40,600	40,400
Gain on sale of mortgage loans	$ 800	$ 1,200