Acquisitions (Narrative) (Details) - Houston Interests, LLC [Member] $ in Thousands	Dec. 12, 2016 USD ($)
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Dec. 12, 2016
Business Acquisition, Name of Acquired Entity	Houston Interests, LLC
Business Combination, Consideration Transferred	$ 42,506

Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=73531572&loc=d3e845-128460

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Acquisition Date
-URI http://asc.fasb.org/extlink&oid=6919109

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=73531572&loc=d3e848-128460

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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Period Type:	duration