INVESTMENT SECURITIES (Maturity Information) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Investments [Line Items]
Total investment securities available for sale, cost	$ 5,192,419	$ 4,029,858
Total investment securities available for sale, fair value	5,226,228	4,056,423
Investment securities held to maturity maturing in one through five years, cost	1,242	12
Investment securities held to maturity maturing in five through ten years, cost	18	1,699
Investment securities held to maturity maturing in over ten years, cost	82	111
Investment securities held to maturity	1,342	1,822
Investment securities held to maturity maturing in one through five years, fair value	1,309	11
Investment securities held to maturity maturing in five through ten years, fair value	11	1,820
Investment securities held to maturity maturing in over ten years, fair value	128	149
Investment securities held to maturity, fair value	1,448	1,980
Debt Securities [Member]
Schedule of Investments [Line Items]
Investment securities available for sale maturing in one year or less, cost	2,288,556	3,238,657
Investment securities available for sale maturing in one through five years, cost	2,323,222	548,459
Investment securities available for sale maturing in five through ten years, cost	194,398	90,605
Investment securities available for sale maturing in over ten years, cost	385,700	151,198
Investment securities available for sale maturing in one year or less, fair value	2,289,859	3,241,415
Investment securities available for sale maturing in one through five years, fair value	2,329,207	549,351
Investment securities available for sale maturing in five through ten years, fair value	196,371	91,087
Investment securities available for sale maturing in over ten years, fair value	394,426	159,257
Equity Securities [Member]
Schedule of Investments [Line Items]
Total investment securities available for sale, cost	543	939
Total investment securities available for sale, fair value	$ 16,365	$ 15,313