Mergers and Acquisitions - Proforma Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Abstract]
Revenue	$ 1,718.6	$ 1,767.5
Net income applicable to common shareholders	$ 23.6	$ 91.7
Earnings per share:
Basic earnings per common share (usd per share)	$ 0.56	$ 2.18
Diluted earnings per common share (usd per share)	$ 0.56	$ 2.18

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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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.

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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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