HELD-TO-MATURITY SECURITIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Held-to-maturity securities [Abstract]
Amortized Cost	$ 0	$ 1,613,019,000
Gross Unrealized Gains		31,368,000
Gross Unrealized Losses		11,696,000
Estimated Fair Value	0	1,632,691,000
Gross gains recognized on held-to-maturity securities	37,000	155,000	113,000
Gross losses recognized on held-to-maturity securities	0	0	2,000
Amortized cost of held-to-maturity securities reclassified to available-for-sale	1,600,000,000
Fair value of held-to-maturity securities reclassified to available-for-sale	1,700,000,000
Increase in other comprehensive income due to transfers to available-for-sale securities	19,700,000
U.S. Government Agencies [Member]
Held-to-maturity securities [Abstract]
Amortized Cost		1,246,649,000
Gross Unrealized Gains		27,082,000
Gross Unrealized Losses		4,320,000
Estimated Fair Value		1,269,411,000
Obligations of States and Political Subdivisions [Member]
Held-to-maturity securities [Abstract]
Amortized Cost		366,370,000
Gross Unrealized Gains		4,286,000
Gross Unrealized Losses		7,376,000
Estimated Fair Value		$ 363,280,000