Commitments and Contingencies (Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($)
Commitment And Contingencies [Line Items]
Remaining minimum distribution payments	$ 3.8
Maximum [Member]
Commitment And Contingencies [Line Items]
Purchase commitment, remaining minimum amount payment date	May 26, 2020

Minimum amount to be expended to satisfy the terms of arrangements in which the entity has agreed to expend funds to procure goods or services, excluding long-term purchase commitments or unconditional purchase obligations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(17))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(19))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(25))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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