Net Income per Common Share (Details) - shares shares in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Stock Option
Securities Included and Excluded from the Computation of Earnings Per Share
Weighted average number of shares included in computation of diluted earnings per share (in shares)	0.3	0.6	0.3	0.6
Weighted average shares excluded from computation of diluted earnings per share (in shares)	0.2	0.0	0.2	0.0
Restricted Stock
Securities Included and Excluded from the Computation of Earnings Per Share
Weighted average number of shares included in computation of diluted earnings per share (in shares)	0.1	0.1	0.2	0.2

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 28A
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1500-109256

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