Fair value measurements (Details 2) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Fair value measurements on a recurring basis
Available-for-sale securities	$ 693,520,000	$ 550,394,000
Level 1 | Interest rate lock commitments
Derivative liabilities
Derivative liabilities	0	0
Fair value measurements on a recurring basis | Level 1
Derivative assets
Derivative assets	2,000	0
Derivative liabilities
Derivative liabilities	0	71,000
Fair value measurements on a recurring basis | Level 1 | Forward sale contracts
Derivative assets
Derivative assets	2,000	0
Derivative liabilities
Derivative liabilities	0	71,000
Fair value measurements on a recurring basis | Level 2
Derivative assets
Derivative assets	452,000	398,000
Derivative liabilities
Derivative liabilities	15,000	43,000
Fair value measurements on a recurring basis | Level 2 | Interest rate lock commitments
Derivative assets
Derivative assets	448,000	393,000
Derivative liabilities
Derivative liabilities	2,000	3,000
Fair value measurements on a recurring basis | Level 2 | Forward sale contracts
Derivative assets
Derivative assets	4,000	5,000
Derivative liabilities
Derivative liabilities	13,000	40,000
Fair value measurements on a recurring basis | Level 2 | Bank
Fair value measurements on a recurring basis
Available-for-sale securities	693,520,000	550,394,000
Fair value measurements on a recurring basis | Level 2 | Other
Fair value measurements on a recurring basis
Money market funds	10,000	10,000
Fair value measurements on a recurring basis | Level 2 | Mortgage-related securities - FNMA, FHLMC and GNMA | Bank
Fair value measurements on a recurring basis
Available-for-sale securities	525,061,000	430,834,000
Fair value measurements on a recurring basis | Level 2 | U.S. Treasury federal agency obligations | Bank
Fair value measurements on a recurring basis
Available-for-sale securities	168,459,000	119,560,000
Fair value measurements on a nonrecurring basis | American Savings Bank (ASB)
Derivative liabilities
Adjustments to fair value of loans held for sale	0	0
Fair value measurements on a nonrecurring basis | Level 3
Derivative liabilities
Loans	658,000	2,445,000
Real estate acquired in settlement of loans		288,000
Estimated fair value
Fair value measurements on a recurring basis
Money market funds	10,000	10,000
Available-for-sale securities	693,520,000	550,394,000
Derivative assets
Derivative assets	454,000	398,000
Derivative liabilities
Derivative liabilities	15,000	114,000
Loans	4,578,184,000	4,578,822,000
Estimated fair value | Level 1
Derivative assets
Derivative assets	2,000	0
Derivative liabilities
Derivative liabilities	0	71,000
Estimated fair value | Level 2
Fair value measurements on a recurring basis
Money market funds	10,000	10,000
Available-for-sale securities	693,520,000	550,394,000
Derivative assets
Derivative assets	452,000	398,000
Derivative liabilities
Derivative liabilities	15,000	43,000
Estimated fair value | Level 3
Derivative liabilities
Loans	4,578,184,000	4,578,822,000
Estimated fair value | Fair value measurements on a nonrecurring basis
Derivative liabilities
Loans	$ 658,000	2,445,000
Real estate acquired in settlement of loans		$ 288,000