Investments (Narrative) (Details) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2015	Dec. 31, 2015
Balance Sheet Related Disclosures [Abstract]
Weighted remaining contractual maturity	9 months 8 days
Realized Gain (Loss) on Marketable Securities, Cost Method Investments, and Other Investments		$ 0
Trading Securities, Unrealized Holding Gain		$ 0

Amount of unrealized holding gain before loss recognized in the income statement for investments in trading securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7(c))
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563

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