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Income Taxes, Net Operating Losses (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
State
Operating Loss Carryforwards [Line Items]
State NOL carryforwards	$ 1,989
Deferred tax asset for State NOL carryforwards	$ 92
State | Minimum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2018
State | Maximum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2037
Federal
Operating Loss Carryforwards [Line Items]
Deferred tax asset for Federal NOL carryforward	$ 11
Federal | Minimum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2018
Federal | Maximum
Operating Loss Carryforwards [Line Items]
Expiration of NOL carryforwards	Dec. 31, 2037

X

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 20
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=96869850&loc=d3e28680-109314

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-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
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-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

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-Name Accounting Standards Codification
-Topic 740
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-Section 25
-Paragraph 20
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Expiration date of each operating loss carryforward included in operating loss carryforward, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
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