Summary of Significant Accounting Policies (Stock-Based Compensation) (Performance-Based Awards) (Details) - Performance-based restricted stock awards	9 Months Ended
Sep. 30, 2018 shares
Performance-Based Restricted Stock Awards Activity [Roll Forward]
Outstanding at the beginning of the period (in shares)	1,664,000
Granted (in shares)	556,000
Released (in shares)	(548,000)
Canceled (in shares)	(330,000)
Outstanding at the end of the period (in shares)	1,342,000

Number of non-option equity instruments released by participants.

No definition available.

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- Definition

Number of shares under non-option equity instrument agreements that were cancelled as a result of occurrence of a terminating event.

+ References

+ Details

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- Definition

Net number of non-option equity instruments granted to participants.

+ References

+ Details

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- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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