INVESTMENT SECURITIES (Details 6) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Scheduled maturities of investment securities available-for sale, amortized cost basis
Due within one year	$ 208,557,000
Due after one year through five years	535,748,000
Due after five years through ten years	623,366,000
Due after ten years	1,231,347,000
Total investment securities available-for-sale	2,599,018,000
Scheduled maturities of investment securities available-for sale, fair value
Due within one year	204,931,000
Due after one year through five years	536,156,000
Due after five years through ten years	615,309,000
Due after ten years	1,250,633,000
Total investment securities available-for-sale	2,607,029,000
Par value of securities pledged to secure public deposits	$ 1,780,000,000	$ 2,170,000,000