Bank subsidiary (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Noninterest expense
Income before income taxes	$ 62,097	$ 41,354	$ 122,184	$ 86,353
Income taxes	22,824	13,742	44,122	29,806
Net income	39,273	27,612	78,062	56,547
American Savings Bank (ASB)
Interest income
Interest and fees on loans	44,473	45,648	89,361	91,745
Interest on investment and mortgage-related securities	3,297	3,793	7,102	7,562
Total interest income	47,770	49,441	96,463	99,307
Interest expense
Interest on deposit liabilities	1,696	2,387	3,475	4,980
Interest on other borrowings	1,214	1,382	2,475	2,749
Total interest expense	2,910	3,769	5,950	7,729
Net interest income	44,860	45,672	90,513	91,578
Provision for loan losses	2,378	2,555	5,924	7,105
Net interest income after provision for loan losses	42,482	43,117	84,589	84,473
Noninterest income
Fees from other financial services	7,463	7,240	14,800	14,186
Fee income on deposit liabilities	4,322	4,599	8,600	9,048
Fee income on other financial products	1,532	1,861	3,081	3,534
Other income	3,634	3,177	7,029	5,556
Total noninterest income	16,951	16,877	33,510	32,324
Noninterest expense
Compensation and employee benefits	18,696	18,166	37,342	35,671
Occupancy	4,241	4,288	8,466	8,528
Data processing	2,489	2,058	4,600	4,028
Services	2,221	1,949	4,004	3,720
Equipment	1,807	1,772	3,537	3,429
Other expense	8,106	7,955	14,813	15,888
Total noninterest expense	37,560	36,188	72,762	71,264
Income before income taxes	21,873	23,806	45,337	45,533
Income taxes	7,684	8,611	15,271	16,487
Net income	$ 14,189	$ 15,195	$ 30,066	$ 29,046