Bank subsidiary (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Noninterest expense
Income before income taxes	$ 64,715	$ 62,097	$ 117,529	$ 122,184
Income taxes	23,654	22,824	42,316	44,122
Net income	41,061	39,273	75,213	78,062
American Savings Bank (ASB)
Interest income
Interest and fees on loans	43,624	44,473	86,227	89,361
Interest on investment and mortgage-related securities	3,234	3,297	6,698	7,102
Total interest income	46,858	47,770	92,925	96,463
Interest expense
Interest on deposit liabilities	1,296	1,696	2,608	3,475
Interest on other borrowings	1,178	1,214	2,342	2,475
Total interest expense	2,474	2,910	4,950	5,950
Net interest income	44,384	44,860	87,975	90,513
Provision (credit) for loan losses	(959)	2,378	899	5,924
Net interest income after provision (credit) for loan losses	45,343	42,482	87,076	84,589
Noninterest income
Fees from other financial services	7,996	7,463	15,639	14,800
Fee income on deposit liabilities	4,433	4,322	8,747	8,600
Fee income on other financial products	1,780	1,532	3,574	3,081
Mortgage banking income	2,003	2,185	5,349	4,220
Gains on sale of securities	1,226	134	1,226	134
Other income	1,731	1,315	3,323	2,675
Total noninterest income	19,169	16,951	37,858	33,510
Noninterest expense
Compensation and employee benefits	20,063	18,696	40,151	37,342
Occupancy	4,219	4,241	8,342	8,466
Data processing	2,827	2,489	5,814	4,600
Services	2,328	2,221	4,431	4,004
Equipment	1,870	1,807	3,644	3,537
Other expense	8,500	8,106	16,095	14,813
Total noninterest expense	39,807	37,560	78,477	72,762
Income before income taxes	24,705	21,873	46,457	45,337
Income taxes	8,786	7,684	16,383	15,271
Net income	$ 15,919	$ 14,189	$ 30,074	$ 30,066