Revenue From Contracts With Customers (Narrative) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Revenue recognized that was included in the contract liability balance at the beginning of the period	$ 40,944
Minimum
Disaggregation of Revenue [Line Items]
Period for installation completion	1 year

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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