CUSTOMER DEPOSIT ACCOUNTS (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
CUSTOMER DEPOSIT ACCOUNTS
Threshold for classifying customer deposit accounts	$ 100,000	$ 100,000	$ 100,000
Customer deposit account balances
Noninterest-bearing demand	3,492,795,000	2,676,466,000
Interest-bearing checking	971,179,000	757,446,000
Money market accounts	4,678,409,000	4,457,376,000
Savings deposits	1,164,618,000	984,518,000
Total core deposits	10,307,001,000	8,875,806,000
Time deposits:
Less than $100,000	2,186,604,000	2,239,836,000
$100,000 or greater	4,959,397,000	4,525,617,000
Total time deposits	7,146,001,000	6,765,453,000
Total deposits	17,453,002,000	15,641,259,000
Time deposits $100 thousand or greater held by the Company's foreign branch located in Hong Kong	$ 264,600,000	$ 481,800,000