STOCKHOLDERS' EQUITY (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		0 Months Ended	1 Months Ended		3 Months Ended	6 Months Ended	0 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	May 02, 2013 Series A Non-Cumulative Perpetual Convertible Preferred Stock	Apr. 30, 2013 Series A Non-Cumulative Perpetual Convertible Preferred Stock	Apr. 30, 2008 Series A Non-Cumulative Perpetual Convertible Preferred Stock	Jun. 30, 2013 Series A Non-Cumulative Perpetual Convertible Preferred Stock	Jun. 30, 2013 Series A Non-Cumulative Perpetual Convertible Preferred Stock	Jan. 23, 2013 Common Stock	Apr. 30, 2013 Common Stock	Jun. 30, 2013 Common Stock	Jun. 30, 2013 Common Stock
Class of Stock
Number of shares issued during the period							200,000
Preferred stock dividend rate (as a percent)							8.00%
Preferred stock liquidation preference (in dollars per share)							$ 1,000
Proceeds from issuance of convertible preferred stock							$ 194.1
Preferred shares converted					85,710
Common stock issued on conversion of convertible preferred stock					5,594,080
Amount of stock repurchase approved by the Board of Directors										200.0
Purchase of treasury stock pursuant to the Stock Repurchase Program, shares			8,026,807	6,784,227
Weighted average price of shares repurchased (in dollars per share)			$ 24.89	$ 22.08
Total cost of repurchase of treasury shares	200.0	150.0	200.0	150.0
Quarterly Dividends
Dividend per share (in dollars per share)						$ 20.00
Preferred stock cash dividends paid								1.7	3.4
Dividend per share (in dollars per share)	$ 0.15	$ 0.10	$ 0.30	$ 0.20							$ 0.15
Common stock cash dividends paid												$ 20.6	$ 41.7