EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended								12 Months Ended
	Apr. 25, 2019	Oct. 31, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Income from continuing operations			$ 130.4	$ 121.6	$ 142.4	$ 178.2	$ 253.1	$ 288.7	$ 223.8	$ 179.9	$ 572.6	$ 945.5	$ 769.2
Less: Dividends declared on preferred stock											2.8
Less: Allocation of undistributed earnings											6.8
Income from continuing operations - basic											563.0	945.5	769.2
(Loss) income from discontinued operations, net of tax			$ (32.9)	$ (229.2)	$ (3.4)	$ (29.1)	$ 31.8	$ 7.8	$ (6.0)	$ (16.0)	(294.6)	17.6	19.5
Net income - basic											$ 268.4	$ 963.1	$ 788.7
Denominator:
Weighted average shares, basic											50,000,000.0	54,900,000	55,700,000
Basic income (loss) attributable to common stockholders per share:
Income from continuing operations (in dollars per share)			$ 2.73	$ 2.47	$ 2.72	$ 3.36	$ 4.69	$ 5.27	$ 4.05	$ 3.25	$ 11.25	$ 17.24	$ 13.82
(Loss) income from discontinued operations (in dollars per share)			(0.70)	(4.69)	(0.07)	(0.55)	0.59	0.14	(0.11)	(0.29)	(5.89)	0.32	0.35
Net income per share (in dollars per share)			$ 2.03	$ (2.22)	$ 2.65	$ 2.81	$ 5.28	$ 5.41	$ 3.94	$ 2.96	$ 5.36	$ 17.56	$ 14.17
Diluted income per share:
Income from continuing operations			$ 130.4	$ 121.6	$ 142.4	$ 178.2	$ 253.1	$ 288.7	$ 223.8	$ 179.9	$ 572.6	$ 945.5	$ 769.2
(Loss) income from discontinued operations, net of tax			$ (32.9)	$ (229.2)	$ (3.4)	$ (29.1)	$ 31.8	$ 7.8	$ (6.0)	$ (16.0)	(294.6)	17.6	19.5
Net income											$ 278.0	$ 963.1	$ 788.7
Denominator:
Weighted average shares, basic											50,000,000.0	54,900,000	55,700,000
Weighted average effect of dilutive securities:
Shares from assumed conversion of preferred stock (in shares)											800,000
Net effect of dilutive stock options and unvested restricted stock (in shares)											100,000	200,000	200,000
Denominator for diluted calculations (in shares)											50,900,000	55,100,000	55,900,000
Diluted income (loss) attributable to common stockholders per share:
Income from continuing operations (in dollars per share)			$ 2.74	$ 2.41	$ 2.71	$ 3.35	$ 4.67	$ 5.25	$ 4.04	$ 3.23	$ 11.24	$ 17.17	$ 13.75
(Loss) income from discontinued operations (in dollars per share)			(0.69)	(4.54)	(0.07)	(0.55)	0.58	0.14	(0.11)	(0.28)	(5.78)	0.32	0.35
Net income per share (in dollars per share)			$ 2.05	$ (2.13)	$ 2.64	$ 2.80	$ 5.25	$ 5.39	$ 3.93	$ 2.95	$ 5.46	$ 17.49	$ 14.10
Series A Non-Voting Convertible Preferred Stock
Diluted income (loss) attributable to common stockholders per share:
Conversion of stock, shares converted		150,000
Conversion of stock, shares issued	150,000
Value Act Holdings, L.P. | Series A Non-Voting Convertible Preferred Stock
Diluted income (loss) attributable to common stockholders per share:
Conversion of stock, shares converted		150,000									150,000
Conversion of stock, shares issued	150,000										150,000
Value Act Holdings, L.P. | Common Stock
Diluted income (loss) attributable to common stockholders per share:
Conversion of stock, shares converted	1,500,000										1,500,000