Stock-Based Compensation (Activity Pertaining To Restricted Stock Awards) (Details) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock - Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, beginning balance	1,301,865	1,213,822	900,286
Weighted average price, beginning balance	$ 23.32	$ 41.29	$ 50.81
Number of shares, granted	659,172	646,451	724,442
Weighted average price, granted	$ 26.07	$ 5.62	$ 34.06
Number of shares, vested	(517,689)	(425,195)	(382,902)
Weighted average price, vested	$ 29.87	$ 43.47	$ 49.69
Number of shares, forfeited	(79,361)	(133,213)	(28,004)
Weighted average price, forfeited	$ 38.87	$ 36.87	$ 45.33
Number of shares, ending balance	1,363,987	1,301,865	1,213,822
Weighted average price, ending balance	$ 21.25	$ 23.32	$ 41.29
Restricted Stock - Non-employee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, beginning balance	111,816	42,064	35,136
Weighted average price, beginning balance	$ 17.21	$ 41.83	$ 50.08
Number of shares, granted	49,104	90,000	25,848
Weighted average price, granted	$ 17.92	$ 12.02	$ 34.04
Number of shares, vested	(43,206)	(20,248)	(18,920)
Weighted average price, vested	$ 21.24	$ 43.46	$ 46.51
Number of shares, forfeited	0	0	0
Weighted average price, forfeited	$ 0.00	$ 0.00	$ 0.00
Number of shares, ending balance	117,714	111,816	42,064
Weighted average price, ending balance	$ 16.03	$ 17.21	$ 41.83
Time Vested \| Restricted Stock - Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, beginning balance	929,737	936,662	724,766
Number of shares, granted	485,799	494,078	576,361
Number of shares, vested	(455,570)	(425,195)	(343,657)
Number of shares, forfeited	(44,408)	(75,808)	(20,808)
Number of shares, ending balance	915,558	929,737	936,662
Performance Shares \| Restricted Stock - Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, beginning balance	372,128	277,160	175,520
Number of shares, granted	173,373	152,373	148,081
Number of shares, vested	(62,119)	0	(39,245)
Number of shares, forfeited	(34,953)	(57,405)	(7,196)
Number of shares, ending balance	448,429	372,128	277,160

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ 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)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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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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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

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ 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)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ 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)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ 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)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

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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No definition available.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option 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)(1)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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