BUSINESS COMBINATION (Details) $ / shares in Units, $ in Millions	May. 29, 2015 USD ($) item $ / shares	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Assets acquired and liabilities assumed
Multi-employer withdrawal liabilities		$ (56.9)
Goodwill		248.3	$ 27.4
Horizon
Business acquisition
Number of Jones Act qualified containerships operated in Alaska | item	4
Business Combination, Ownership Percentage	100.00%
Price of Warrant (in dollars per share) | $ / shares	$ 0.72
Number of ship acquired | item	7
Assets acquired and liabilities assumed
Cash and cash equivalent	$ 0.8
Accounts receivable	31.7
Other current assets	7.2
Deferred tax assets, net	38.9
Property and equipment	170.4
Intangibles - Customer relationships	140.0
Other long-term assets	4.1
Accounts payable	(22.8)
Accruals and other current liabilities	(32.1)
Multi-employer withdrawal liabilities	(60.6)
Capital lease obligations	(1.6)
Horizon's debt and warrants	(467.5)
Total identifiable assets less liabilities	(191.5)
Total cash paid for common shares	(29.4)
Goodwill	$ 220.9	220.9
Horizon | Customer relationships
Assets acquired and liabilities assumed
Intangibles - Customer relationships		$ 140.0
Expected useful lives	21 years
Horizon | Pasha | Horizon Hawaii Operations
Business acquisition
Pasha transaction proceeds	$ 141.5
Horizon | As previously Reported
Total cash consideration
Common shares	29.4
Warrants	37.1
Horizon's debt (including accrued interest and breakage fees)	428.9
Total	495.4
Assets acquired and liabilities assumed
Cash and cash equivalent	0.8
Accounts receivable	31.7
Other current assets	7.1
Deferred tax assets, net	38.9
Property and equipment	171.0
Intangibles - Customer relationships	140.0
Other long-term assets	5.0
Accounts payable	(23.2)
Accruals and other current liabilities	(32.1)
Multi-employer withdrawal liabilities	(60.6)
Capital lease obligations	(1.4)
Horizon's debt and warrants	(467.5)
Total identifiable assets less liabilities	(190.3)
Total cash paid for common shares	(29.4)
Goodwill	219.7
Horizon | Adjustments
Assets acquired and liabilities assumed
Other current assets	0.1
Property and equipment	(0.6)
Other long-term assets	(0.9)
Accounts payable	0.4
Capital lease obligations	(0.2)
Total identifiable assets less liabilities	(1.2)
Goodwill	$ 1.2