CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	4 Months Ended	5 Months Ended	12 Months Ended
Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Unrealized gains (losses) on available-for-sale securities, tax	$ 0	$ 0	$ 0	$ 0
Change in supplemental executive retirement plan pension liability, tax	0	0	0	0
Change in Pension Plan minimum liability, tax	0	0	0	0
Change in Other Benefit Plan minimum liability, tax	$ 0	$ 0	$ 0	$ 0

Other Comprehensive Income Pension Plan Minimum Liability Adjustment Tax Period Increase Decrease

No definition available.

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- Definition

Other Comprehensive Income Supplemental Executive Retirement Plan Minimum Liability Adjustment Tax Period Increase Decrease

+ References

No definition available.

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- Definition

Amount, after reclassification adjustment, of tax (expense) benefit for (increase) decrease in accumulated other comprehensive income of defined benefit plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (i-k)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683

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- Definition

Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

+ References

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- References

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