SIGNIFICANT ACCOUNTING POLICIES - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Accumulated amortization	$ (56.8)	$ (47.6)
Total assets	53.8	54.4
In-place/favorable leases
Finite-Lived Intangible Assets [Line Items]
Amortized intangible assets:	69.9	62.6
Favorable leases
Finite-Lived Intangible Assets [Line Items]
Amortized intangible assets:	17.9	16.6
Permitted quarry rights
Finite-Lived Intangible Assets [Line Items]
Amortized intangible assets:	18.0	18.0
Contract backlog
Finite-Lived Intangible Assets [Line Items]
Amortized intangible assets:	2.6	2.6
Trade name/customer relationships
Finite-Lived Intangible Assets [Line Items]
Amortized intangible assets:	$ 2.2	$ 2.2