Fair Value Of Financial Instruments (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($) agreement	Mar. 31, 2018 USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Other comprehensive loss	$ (209)	$ 467
Accumulated other comprehensive income
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Other comprehensive loss	(209)	$ 467
Accumulated other comprehensive income \| One of our equity method investees
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Other comprehensive loss	$ 200
Fair Value, Measurements, Recurring [Member] \| Interest Rate Swap [Member] \| One of our equity method investees
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Number of interest rate swap agreements \| agreement	2

Amount after tax and reclassification adjustments of other comprehensive income (loss).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669619-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 55
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=109228884&loc=d3e1436-108581

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669625-108580

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