Stock-Based Compensation - Nonvested performance share units (Details) - Performance Shares - $ / shares shares in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2020
Total Stockholder Return
Number of shares (thousands)
Nonvested beginning balance (in shares)	374	382	240	240
Granted (in shares)	2		142
Forfeited (in shares)	(5)	(8)
Nonvested ending Balance (in shares)	371	374	382	371
Weighted average grant date fair value
Nonvested weighted average exercise price beginning balance (in dollar per share)	$ 47.97	$ 48.02	$ 64.61	$ 64.61
Granted the weighted average exercise price (in dollar per share)	28.55		28.55
Forfeited weighted average exercise price (in dollar per share)	73.11	50.17
Nonvested weighted average exercise price ending balance (in dollar per share)	$ 47.60	$ 47.97	$ 48.02	$ 47.60
Relative Revenue Growth
Number of shares (thousands)
Nonvested beginning balance (in shares)	374	382	240	240
Granted (in shares)	2		142
Forfeited (in shares)	(5)	(8)
Nonvested ending Balance (in shares)	371	374	382	371
Weighted average grant date fair value
Nonvested weighted average exercise price beginning balance (in dollar per share)	$ 41.52	$ 41.54	$ 48.52	$ 48.52
Granted the weighted average exercise price (in dollar per share)	37.77		34.11
Forfeited weighted average exercise price (in dollar per share)	52.64	42.35
Nonvested weighted average exercise price ending balance (in dollar per share)	$ 41.35	$ 41.52	$ 41.54	$ 41.35
Adjusted Earnings Per Share
Number of shares (thousands)
Nonvested beginning balance (in shares)	112	115	0	0
Granted (in shares)	2		115
Forfeited (in shares)	0	(3)
Nonvested ending Balance (in shares)	114	112	115	114
Weighted average grant date fair value
Nonvested weighted average exercise price beginning balance (in dollar per share)	$ 34.11	$ 34.11	$ 0	$ 0
Granted the weighted average exercise price (in dollar per share)	37,770,000		34.11
Forfeited weighted average exercise price (in dollar per share)	0	34.11
Nonvested weighted average exercise price ending balance (in dollar per share)	$ 34.16	$ 34.11	$ 34.11	$ 34.16

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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-SubTopic 10
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-Paragraph 2
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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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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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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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