QUARTERLY FINANCIAL INFORMATION (Unaudited) (Details) (USD $) In Millions, except Per Share data, 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
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 1,710.7	$ 1,129.7	$ 1,116.0	$ 1,678.2	$ 1,197.2	$ 927.7	$ 839.6	$ 1,247.9	$ 5,634.6	$ 4,212.4	$ 4,685.9
Operating income (loss)	226.2	55.3	(6.9)	293.1	118.8	108.5	87.1	153.1	567.7	467.5	406.8
Net income (loss) from continuing operations	132.3	39.4	(3.9)	182.2	69.2	74.3	51.7	98.8	350.0	294.0	230.0
Net income (loss)	132.4	38.8	(4.7)	188.3	68.7	66.3	49.6	99.7	354.8	284.3	230.5
Net income (loss) attributed to common shareholders	$ 131.6	$ 38.1	$ (5.4)	$ 187.5	$ 68.0	$ 65.7	$ 48.8	$ 98.9	$ 351.8	$ 281.4	$ 227.4
Earnings (loss) per common share (basic)
Net income (loss) from continuing operations (in dollars per share)	$ 1.64	$ 0.49	$ (0.06)	$ 2.30	$ 0.87	$ 0.94	$ 0.65	$ 1.25	$ 4.37	$ 3.70	$ 2.89
Discontinued operations, net of tax (in dollars per share)	$ 0.00	$ (0.01)	$ (0.01)	$ 0.08	$ 0.00	$ (0.10)	$ (0.03)	$ 0.01	$ 0.06	$ (0.12)	$ 0.00
Earnings per common share (basic) (in dollars per share)	$ 1.64	$ 0.48	$ (0.07)	$ 2.38	$ 0.87	$ 0.84	$ 0.62	$ 1.26	$ 4.43	$ 3.58	$ 2.89
Earnings (loss) per common share (diluted)
Net income (loss) from continuing operations (in dollars per share)	$ 1.63	$ 0.48	$ (0.06)	$ 2.29	$ 0.86	$ 0.93	$ 0.65	$ 1.24	$ 4.33	$ 3.67	$ 2.87
Discontinued operations, net of tax (in dollars per share)	$ 0.00	$ (0.01)	$ (0.01)	$ 0.08	$ 0.00	$ (0.10)	$ (0.03)	$ 0.01	$ 0.06	$ (0.12)	$ 0.00
Earnings per common share (diluted) (in dollars per share)	$ 1.63	$ 0.47	$ (0.07)	$ 2.37	$ 0.86	$ 0.83	$ 0.62	$ 1.25	$ 4.39	$ 3.55	$ 2.87