Share-Based Compensation - Stock Option Activity Table (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	1 Months Ended	12 Months Ended
Feb. 09, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance (in shares)	20	90
Granted (in shares)	0	0
Exercised (in shares)	0	0
Expired (in shares)	(1)	(23)
Forfeited (in shares)	(19)	(47)
Outstanding, ending balance (in shares)	0	20	90
Weighted Average Exercise Price Per Share
Outstanding, beginning balance (in usd per share)	$ 1,429.11	$ 1,420.9
Granted (in usd per share)	0	0
Exercised (in usd per share)	0	0
Expired (in usd per share)	741.86	914.50
Forfeited (in usd per share)	1,452.4	1,666.21
Outstanding, ending balance (in usd per share)	$ 0	$ 1,429.11	$ 1,420.9
Options outstanding, weighted average contract life		4 years 3 months 7 days	5 years 8 months 12 days
Options outstanding, aggregate intrinsic value	$ 0	$ 0	$ 0
Options exercised, aggregate intrinsic value	$ 0	$ 0
Options exercisable, shares underlying options (in shares)	0	19
Options exercisable, average exercise price per share (in usd per share)	$ 0	$ 1,439.55
Options exercisable, weighted average contract life		4 years 4 months 6 days
Options exercisable, aggregate intrinsic value	$ 0	$ 0

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of non-vested options forfeited.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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