INCOME TAXES - Schedule of Tax effects of Temporary Differences Affecting Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Employee benefits	$ 35.8	$ 37.1
Capitalized costs	23.0	22.4
Joint ventures and other investments	1.3	4.3
Impairment and amortization	11.4	7.8
Solar investment benefits	15.0	9.0
Insurance and other reserves	6.0	5.9
Other	3.5	5.7
Total deferred tax assets	96.0	92.2
Deferred tax liabilities:
Property (including tax-deferred gains on real estate transactions)	260.3	279.3
Straight-line rental income and advanced rent	8.4	9.0
Other	9.3	6.0
Total deferred tax liabilities	278.0	294.3
Net deferred tax liability	$ 182.0	$ 202.1