SECURITIES SOLD UNDER REPURCHASE AGREEMENTS AND OTHER BORROWINGS (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2012
Amount of securities sold under repurchase agreements
Total	$ 995,000,000	$ 995,000,000
Other disclosures
Total interest expense recorded on repurchase agreements	41,381,000	46,166,000	48,561,000
Other borrowings		20,000,000
Securities Sold Under Repurchase Agreements
Securities sold under repurchase agreements and other borrowings
Amount of long-term repurchase agreements modified		150,000,000		200,000,000
Reduction in interest rates on long-term repurchase agreements modified (as a percent)		1.95%		0.86%
Amount of securities sold under repurchase agreements
Total	995,000,000	995,000,000
Interest rate on securities sold under repurchase agreements
Total (as a percent)	4.06%	4.30%
Other disclosures
Total interest expense recorded on repurchase agreements	41,400,000	46,200,000	48,600,000
Available borrowing capacity from repurchase agreements	811,100,000	1,190,000,000
Securities Sold Under Repurchase Agreements | Minimum
Securities sold under repurchase agreements and other borrowings
Interest rates on long-term repurchase agreements (as a percent)	2.49%
Securities Sold Under Repurchase Agreements | Maximum
Securities sold under repurchase agreements and other borrowings
Interest rates on long-term repurchase agreements (as a percent)	5.01%
Securities Sold Under Repurchase Agreements | Maturities in Year Three
Amount of securities sold under repurchase agreements
Total	245,000,000	245,000,000
Interest rate on securities sold under repurchase agreements
Total (as a percent)	4.49%	4.49%
Securities Sold Under Repurchase Agreements | Maturities in Year Four
Amount of securities sold under repurchase agreements
Total	250,000,000	350,000,000
Interest rate on securities sold under repurchase agreements
Total (as a percent)	5.01%	4.96%
Securities Sold Under Repurchase Agreements | Maturities in Year Five
Amount of securities sold under repurchase agreements
Total	50,000,000	50,000,000
Interest rate on securities sold under repurchase agreements
Total (as a percent)	4.15%	4.15%
Securities Sold Under Repurchase Agreements | Maturities in year ten
Amount of securities sold under repurchase agreements
Total	350,000,000	350,000,000
Interest rate on securities sold under repurchase agreements
Total (as a percent)	3.51%	3.53%
Securities Sold Under Repurchase Agreements | Maturities in year Eleven
Amount of securities sold under repurchase agreements
Total	100,000,000
Interest rate on securities sold under repurchase agreements
Total (as a percent)	2.49%
Short term borrowings
Other disclosures
Other borrowings	$ 0	$ 20,000,000
Maturity period of debt		2 days
Annual interest rate (as a percent)		0.25%