Share-Based Compensation - Narrative (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Share-Based Compensation
Percentage increments vested on anniversaries of the grant date	25.00%
Par value, common stock	$ 0.01	$ 0.01
Cash Settled RSU Plan
Share-Based Compensation
Vesting period	4 years
Percentage increments vested on anniversaries of the grant date	25.00%
Number of share of par value $0.01 on which lump sum cash payment is received by RSU holders	1
Par value, common stock	$ 0.01
Number of shares of common stock on which each RSU holders are entitled to dividend equivalent payments	1
Restricted stock units awarded	0
1998 Stock Incentive Plan ("SI Plan")
Share-Based Compensation
Maximum number of shares of common stock authorized for issuance	40,400,000
Number of shares of common stock available for issuance	5,255,495

Face amount or stated value per share of common stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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Number of shares authorized for issuance under share-based payment arrangement.

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Percentage of vesting of award under share-based payment arrangement.

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Represents the number of shares of common stock on which each RSU holders are entitled to dividend equivalent payments.

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