Significant transactions - Armada Acquisition - Supplemental Pro Forma Information (Details) - Armada - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Supplemental Pro Forma Information
Total revenues	$ 1,144.6	$ 1,032.6
Net income	$ (155.1)	$ 45.9

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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