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BUSINESS COMBINATION - CONSIDERATION PAID (Details) - USD ($) $ in Millions			3 Months Ended	9 Months Ended
	Aug. 04, 2016	May 29, 2015	Sep. 30, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Assets acquired and liabilities assumed
Goodwill			$ 324.1	$ 324.1	$ 245.1	$ 241.6	$ 241.6	$ 248.3	$ 247.1	$ 27.4	$ 27.4
Repayments of Span Alaska debt				81.9
Span Alaska
Business acquisition
Percentage interest acquired	100.00%
Number of years in operation	38 years
Total cash consideration
Membership interests consideration	$ 117.2
Total debt assumed	81.9
Total payments	199.1
Assets acquired and liabilities assumed
Cash and cash equivalents	4.4
Accounts receivable	11.1
Other current and long-term assets	1.0
Property and equipment	8.1
Intangibles – Customer relationships	79.0
Intangibles – Trade name	27.3
Accounts payable	(3.3)
Accruals and other current liabilities	(6.3)
Capital lease obligations	(1.2)
Debt	(81.9)
Total identifiable assets less liabilities	38.2
Membership interests consideration	117.2
Goodwill	79.0
Repayments of Span Alaska debt	81.9
Total cash paid for common shares	(117.2)
Condensed Consolidated Statements of Income and Comprehensive Income
Operating revenue			8.5	8.5
Operating Income			1.3	1.3
One-time acquisition related costs			2.9	2.9
Span Alaska \| Trade Names
Assets acquired and liabilities assumed
Intangibles – Trade name	27.3
Span Alaska \| Customer relationships
Assets acquired and liabilities assumed
Intangibles – Customer relationships	$ 79.0
Expected useful lives	20 years
Horizon
Total cash consideration
Total debt assumed		$ 428.9
Total payments		495.4
Assets acquired and liabilities assumed
Goodwill		217.7
Common shares		29.4
Warrants		$ 37.1
Condensed Consolidated Statements of Income and Comprehensive Income
Operating revenue			74.0	208.2
Operating Income			$ 11.3	$ 21.6