Bank segment - Mortgage servicing rights (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Servicing Asset at Amortized Cost [Line Items]
Repurchase reserve						$ 100,000		$ 100,000.0
American Savings Bank (ASB)
Servicing Asset at Amortized Cost [Line Items]
Mortgage service fees	$ 700,000	$ 900,000	$ 2,100,000	$ 2,700,000
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing asset - beginning balance			8,884,000
Servicing asset - ending balance	9,191,000		9,191,000		$ 8,884,000
American Savings Bank (ASB) | Residential loan
Servicing Asset at Amortized Cost [Line Items]
Proceeds from sale of mortgage loans	70,000,000	58,200,000	168,500,000	231,500,000
Gain on sale of mortgage loans	2,400,000	1,400,000	5,100,000	5,300,000
American Savings Bank (ASB) | Mortgage Servicing Rights (MSR)
Servicing Asset at Amortized Cost [Line Items]
Gross carrying amount						16,475,000	$ 14,531,000
Accumulated amortization						(7,284,000)	(5,647,000)
Valuation allowance	0	0	0	(209,000)	(209,000)	0	0	0
Net carrying amount						9,191,000	8,884,000	$ 12,258,000
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing asset - beginning balance			8,884,000	11,749,000	11,749,000
Amount capitalized			1,944,000	2,636,000
Amortization			(1,637,000)	(2,123,000)
Other-than-temporary impairment			0	(4,000)
Servicing asset - ending balance	9,191,000	12,258,000	9,191,000	12,258,000	8,884,000
Valuation Allowance [Roll Forward]
Valuation allowance, beginning balance			0	209,000	209,000
Provision (recovery)			0	(205,000)
Other-than-temporary impairment			0	(4,000)
Valuation allowance, ending balance	$ 0	$ 0	$ 0	$ 0	$ 0
Unpaid principal balance						1,160,266,000	1,097,314,000
Weighted average note-rate			4.00%		4.05%
Weighted average discount rate			9.40%		9.60%
Weighted average prepayment speed			12.40%		9.30%
Prepayment rate - 25 points adverse rate change						(533,000)	(561,000)
Prepayment rate - 50 points adverse rate change						(952,000)	(1,104,000)
Discount rate - 25 points adverse rate change						(90,000)	(111,000)
Discount rate - 50 points adverse rate change						$ (179,000)	$ (220,000)
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%