Bank segment - Mortgage servicing rights (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
American Savings Bank (ASB)
Servicing Asset at Amortized Cost [Line Items]
Mortgage service fees	$ 900	$ 900
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing Asset at Amortized Cost	11,540
Servicing Asset at Amortized Cost	11,965
American Savings Bank (ASB) | Mortgage Servicing Rights (MSR)
Servicing Asset at Amortized Cost [Line Items]
Gross carrying amount			$ 28,090	$ 26,097
Accumulated amortization			(16,084)	(14,138)
Valuation allowance	(209)	(251)	(41)	(202)
Net carrying amount			11,965	11,757
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing Asset at Amortized Cost	11,749	11,938
Servicing Asset at Amortized Value, Amount Capitalized	906	467
Servicing Asset at Amortized Cost, Amortization	(647)	(432)
Other-than-temporary impairment	(2)	(14)
Servicing Asset at Amortized Cost	12,006	11,959
Valuation Allowance [Roll Forward]
Valuation allowance, beginning balance	209	251
Provision (recovery)	(166)	(35)
Other-than-temporary impairment	(2)	(14)
Valuation allowance, ending balance	$ 41	$ 202
Unpaid principal balance			1,414,990	1,391,030
Weighted average note-rate	4.06%	4.07%
Weighted average discount rate	9.60%	9.60%
Weighted average prepayment speed	10.60%	9.50%
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 25 Basis Point Adverse Change in Prepayment Speed			(750)	(757)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Point Adverse Change in Prepayment Speed			(1,408)	(1,524)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 25 Basis Points Adverse Change in Discount Rate			(129)	(140)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Points Adverse Change in Discount Rate			$ (256)	$ (278)
Troubled debt restructurings real estate loans
Servicing Asset at Amortized Cost [Line Items]
Financing Receivable Modifications Minimum, Period of Payment Default of Loans Determined to be Troubled Debt Restructurings	90 days