Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Allocated share-based compensation expense	$ 3.1	$ 2.4
Restricted Stock Units (RSUs) [Member]
Share-based compensation shares granted	918,155
Weighted average grant date fair value	$ 5.51
Share-based compensation vesting period	3 years
Restricted Stock Units (RSUs) [Member] \| Non-Employee Board Of Directors [Member]
Share-based compensation vesting period	1 year
Restricted Stock Units (RSUs) [Member] \| Vest on One Year Anniversary [Member]
Share-based compensation shares granted	799,317
Restricted Stock Units (RSUs) [Member] \| Vest on One Year Anniversary [Member] \| Non-Employee Board Of Directors [Member]
Share-based compensation shares granted	118,838
Equivalent Stock Units (ESUs) [Member]
Share-based compensation shares granted	610,570
Weighted average grant date fair value	$ 5.51
Share-based compensation vesting period	3 years
Performance Stock Unit Awards (PSUs) [Member]
Share-based compensation shares granted	377,334
Weighted average grant date fair value	$ 6.50
Share-based compensation award vesting period	3 years
Performance Stock Unit Awards (PSUs) [Member] \| Minimum [Member]
Number of common stock shares issued for each PSU	0
Performance Stock Unit Awards (PSUs) [Member] \| Maximum [Member]
Number of common stock shares issued for each PSU	2
Performance Stock Unit Awards (PSUs) [Member] \| 50th percentile relative TSR [Member]
Percentage of vesting of share-based compensation awards	65.00%
Performance Stock Unit Awards (PSUs) [Member] \| 90th percentile relative TSR [Member]
Percentage of vesting of share-based compensation awards	200.00%

Share Based Compensation Arrangement Number Of Common Stock Shares Issued For Each Performance Stock Unit Awards

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Percentage of vesting of share-based compensation awards.

+ References

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