Bank segment (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net income	$ 41,894	$ 41,061	$ 88,294	$ 75,213
Net unrealized gains (losses) on securities:
Net unrealized gains (losses) on securities arising during the period, net of (taxes) benefits, of $1,049 and ($689) for the three months ended September 30, 2013 and 2012 and $7,081 and ($1,261) for the nine months ended September 30, 2013 and 2012, respectively	2,543	(8,307)	5,063	(9,135)
Net unrealized gains (losses) on securities arising during the period, (taxes) benefits	(1,679)	5,485	(3,343)	6,032
Less: reclassification adjustment for net realized gains, included in net income, net of taxes, of nil for the three months ended September 30, 2013 and 2012 and $488 and $53 for the nine months ended September 30, 2013 and 2012, respectively	0	(738)	(1,715)	(738)
Less: reclassification adjustment for net realized gains included in net income, taxes	0	488	1,132	488
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,647, $3,195, $3,252 and $6,590 for the respective periods	2,873	5,680	5,686	11,701
Less: amortization of net loss, prior service gain and transition obligation included in net periodic benefit cost, tax benefits	(1,742)	(3,630)	(3,538)	(7,476)
Other comprehensive income (loss), net of taxes	2,900	(8,305)	4,067	(8,366)
Comprehensive income	44,321	32,283	91,415	65,901
American Savings Bank (ASB)
Net income	11,676	15,919	26,215	30,074
Net unrealized gains (losses) on securities:
Net unrealized gains (losses) on securities arising during the period, net of (taxes) benefits, of $1,049 and ($689) for the three months ended September 30, 2013 and 2012 and $7,081 and ($1,261) for the nine months ended September 30, 2013 and 2012, respectively	2,543	(8,307)	5,063	(9,135)
Net unrealized gains (losses) on securities arising during the period, (taxes) benefits	1,679	(5,485)	3,343	(6,032)
Less: reclassification adjustment for net realized gains, included in net income, net of taxes, of nil for the three months ended September 30, 2013 and 2012 and $488 and $53 for the nine months ended September 30, 2013 and 2012, respectively	0	738	(1,715)	(738)
Less: reclassification adjustment for net realized gains included in net income, taxes	0	(488)	1,132	488
Retirement benefit plans:
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $1,647, $3,195, $3,252 and $6,590 for the respective periods	215	466	434	2,623
Less: amortization of net loss, prior service gain and transition obligation included in net periodic benefit cost, tax benefits	142	308	(286)	(1,732)
Other comprehensive income (loss), net of taxes	2,758	(8,579)	3,782	(7,250)
Comprehensive income	$ 14,434	$ 7,340	$ 29,997	$ 22,824