INCOME TAXES - Federal Tax Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation between reported income tax expense (benefit) and income taxes calculated by the statutory federal income tax rate
Tax expense at statutory federal rate of 35%	$ 87.0	$ 50.0	$ 52.0
State income taxes, net of federal income tax benefit	16.0	18.0	5.0
Expired state net operating losses, net of federal income tax benefit	35.0	11.0	34.0
Tax attributable to noncontrolling interests	(106.0)	(59.0)	(23.0)
Nondeductible goodwill	29.0	22.0
Nontaxable gains	(11.0)	(11.0)
Nondeductible litigation costs	37.0	44.0
Nondeductible acquisition costs	1.0	4.0	2.0
Nondeducible health insurance provider fee	2.0	2.0	3.0
Changes in valuation allowance	(25.0)	4.0	(20.0)
Change in tax contingency reserves, including interest	(9.0)	7.0	(2.0)
Amendment of prior-year tax returns		(17.0)
Prior-year provision to return adjustment and other changes in deferred taxes	12.0	(12.0)	(5.0)
Other items	(1.0)	5.0	3.0
Income tax expense (benefit)	$ 67.0	$ 68.0	$ 49.0
Statutory federal rate (as a percent)	35.00%	35.00%	35.00%