Other Operating Costs (Benefit) (Schedule of Activity for Restructured Real Estate) (Details) - Office Space Reductions [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Balance at December 31	$ 3,060	$ 3,083
Cost (benefit) to operations during the year ended December 31	(40)	509
Utilized during the year ended December 31	(1,340)	(532)
Balance at December 31	$ 1,680	$ 3,060

Costs (benefit) to operation during year.

No definition available.

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Balance Type:	debit
Period Type:	duration

- 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.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in the accrual for restructuring costs.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: