INVESTMENT SECURITIES, Unrealized Losses and Corporate Debt Securities (Details) (USD $)	Jun. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Investment grade corporate debt securities available-for-sale	$ 1,120,000,000
Total investment securities available-for-sale portfolio (in hundredths)	35.00%
Number of securities in a continuous unrealized loss position for more than twelve months	8
Number of individual securities with a continuous unrealized loss position	96
Scheduled maturities of investment securities available-for sale, amortized cost basis [Abstract]
Due within one year	1,313,357,000
Due after one year through five years	350,888,000
Due after five years through ten years	767,516,000
Due after ten years	768,426,000
Total investment securities available-for-sale	3,200,187,000
Scheduled maturities of investment securities available-for sale, fair value [Abstract]
Due within one year	1,309,062,000
Due after one year through five years	353,157,000
Due after five years through ten years	761,926,000
Due after ten years	781,963,000
Total investment securities available-for-sale	3,206,108,000
US Government Agencies and Government Sponsored Enterprise Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of individual securities with a continuous unrealized loss position	15
Residential Mortgage Backed Securities Issued By US Government Agencies And Government Sponsored Enterprise [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of individual securities with a continuous unrealized loss position	10
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of individual securities with a continuous unrealized loss position	4
Corporate Debt Securities [Member] | Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities in a continuous unrealized loss position for more than twelve months	3
Corporate debt securities at estimated fair value	39,500,000
Number of individual securities with a continuous unrealized loss position	64
Gross unrealized losses, trust preferred securities, portion representing impairment loss on securities not other-than-temporarily-impaired	4,400,000
Corporate Debt Securities [Member] | Non-investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of individual securities with a continuous unrealized loss position	1
Percentage of total amortized cost basis of corporate debt securities (in hundredths)	1.00%
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of individual securities with a continuous unrealized loss position	2
Trust Preferred Securties [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities in a continuous unrealized loss position for more than twelve months	5
Trust preferred securities at estimated fair value	$ 10,700,000
Trust preferred securities as a percentage of total investment securities available-for-sale portfolio (in hundredths)	1.00%
Percentage of total amortized cost basis of these securities (in hundredths)	47.00%