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Legal Proceedings (Narrative) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2017 USD ($)
Stone & Youngberg [Member] |
Loss Contingencies [Line Items] |
Loss contingency, damages sought, value | $ 200.0
CA Funds [Member] |
Loss Contingencies [Line Items] |
Loss contingency, damages sought, value | $ 90.0
Loss contingency, damages sought | In a related action, approximately one dozen individual investors (the “individual plaintiffs”) brought a direct action against the Company and other defendants, seeking recessionary damages of approximately $90 million.
Loss contingency, actions taken by court | The court ruled that the individual plaintiffs had no standing to pursue these claims because the CA funds are separately pursuing claims.

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- Definition Describes important rulings or decisions made by the judge, arbitrator or mediator in the legal matter that could impact the outcome of the case. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349 + Details
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- Definition Describes the form and magnitude of the award the plaintiff seeks in the legal matter, which may include an unspecified amount of money. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 + Details
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