Summary Of Significant Accounting Policies (Liabilities Subject to Compromise) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Accrued interest on senior notes	$ 35,794
Total	1,335,794
7.125% Senior Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Senior unsecured notes	800,000
7.750% Senior Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Senior unsecured notes	$ 500,000

Total amount of liabilities subject to compromise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120604989&loc=d3e56015-112765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56145-112766

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=116635682&loc=d3e55717-112764

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