INVESTMENT SECURITIES (Maturity Information) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Schedule of Investments [Line Items]
Total investment securities available for sale, cost	$ 4,029,858	$ 4,486,881
Total investment securities available for sale, fair value	4,056,423	4,510,076
Investment securities held to maturity maturing in one through five years, cost	12	0
Investment securities held to maturity maturing in five through ten years, cost	1,699	2,404
Investment securities held to maturity maturing in over ten years, cost	111	128
Investment securities held to maturity	1,822	2,532
Investment securities held to maturity maturing in one through five years, fair value	11	0
Investment securities held to maturity maturing in five through ten years, fair value	1,820	2,570
Investment securities held to maturity maturing in over ten years, fair value	149	171
Investment securities held to maturity, fair value	1,980	2,741
Debt Securities [Member]
Schedule of Investments [Line Items]
Investment securities available for sale maturing in one year or less, cost	3,238,657	3,441,185
Investment securities available for sale maturing in one through five years, cost	548,459	916,101
Investment securities available for sale maturing in five through ten years, cost	90,605	1,683
Investment securities available for sale maturing in over ten years, cost	151,198	126,857
Investment securities available for sale maturing in one year or less, fair value	3,241,415	3,436,818
Investment securities available for sale maturing in one through five years, fair value	549,351	921,536
Investment securities available for sale maturing in five through ten years, fair value	91,087	1,710
Investment securities available for sale maturing in over ten years, fair value	159,257	130,781
Equity Securities [Member]
Schedule of Investments [Line Items]
Total investment securities available for sale, cost	939	1,055
Total investment securities available for sale, fair value	$ 15,313	$ 19,231