STOCKHOLDERS' EQUITY AND EARNINGS PER SHARE (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reclassifications out of accumulated other comprehensive income
Net gain on sales of investment securities									$ 12,089	$ 757	$ 9,703
Other operating income									34,801	24,633	12,505
Total before tax	98,564	108,906	111,870	106,510	108,200	105,203	104,394	107,795	425,850	425,592	383,334
Tax expense	(22,782)	(35,749)	(37,855)	(34,419)	(36,300)	(34,093)	(33,837)	(39,712)	(130,805)	(143,942)	(138,100)
NET INCOME	75,782	73,157	74,015	72,091	71,900	71,110	70,557	68,083	295,045	281,650	245,234
Amount Reclassified from Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income
NET INCOME									7,295	452	5,663
Investment securities available for sale | Amount Reclassified from Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income
Total before tax									12,089	757	9,703
Tax expense									(5,077)	(318)	(4,075)
NET INCOME									7,012	439	5,628
Investment securities available for sale | Realized net gains on sale of securities | Amount Reclassified from Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income
Net gain on sales of investment securities									12,089	757	9,703
Other investments | Amount Reclassified from Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income
Total before tax									488	23	61
Tax expense									(205)	(10)	(26)
NET INCOME									283	13	35
Other investments | Realized net gain on sale of other investments | Amount Reclassified from Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income
Other operating income									$ 488	$ 23	$ 61