Bank segment - Mortgage servicing rights (Details) - American Savings Bank (ASB) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2014
Servicing Asset at Amortized Cost [Line Items]
Mortgage service fees	$ 900	$ 900	$ 1,800	$ 1,700
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing Asset at Amortized Cost			11,540
Servicing Asset at Amortized Cost	12,265		12,265		$ 11,540
Mortgage Servicing Rights (MSR)
Servicing Asset at Amortized Cost [Line Items]
Gross carrying amount	29,182	26,357
Accumulated amortization	(16,880)	(14,578)
Valuation allowance	(37)	(174)	(209)	(251)	(251)	$ (209)
Net carrying amount	12,265	11,605
Movement in Mortgage Loans on Real Estate [Roll Forward]
Servicing Asset at Amortized Cost			11,749	11,938	11,938
Servicing Asset at Amortized Value, Amount Capitalized			2,001	753
Servicing Asset at Amortized Cost, Amortization			(1,444)	(872)
Other-than-temporary impairment			(4)	(40)
Servicing Asset at Amortized Cost	12,302	11,779	12,302	11,779	11,749
Valuation Allowance [Roll Forward]
Valuation allowance, beginning balance			209	251	251
Provision (recovery)			(168)	(37)
Other-than-temporary impairment			(4)	(40)
Valuation allowance, ending balance	37	$ 174	$ 37	$ 174	$ 209
Unpaid principal balance	1,467,492					1,391,030
Weighted average note-rate			4.02%		4.07%
Weighted average discount rate			9.50%		9.60%
Weighted average prepayment speed			11.00%		9.50%
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 25 Basis Point Adverse Change in Prepayment Speed	(814)					(757)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Point Adverse Change in Prepayment Speed	(1,537)					(1,524)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 25 Basis Points Adverse Change in Discount Rate	(132)					(140)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 Basis Points Adverse Change in Discount Rate	$ (262)					$ (278)