Reduction in Value of Assets (Components of the Expense) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reduction In Value Of Assets [Abstract]
Reduction in value of goodwill				$ 668,900	$ 251,826
Reduction in value of long-lived assets				17,185	70,887	$ 10,390
Total reduction in value of assets	$ 9,628	$ 7,557	$ 322,713	$ 17,185	$ 322,713	$ 10,390

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266

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