Stock Compensation Plans - Nonvested Share Activity (Details)	12 Months Ended
Dec. 31, 2020 $ / shares shares
Performance Share Units
Summary of Activity Related to Share-based Compensation
Unvested units, beginning of period (in shares) \| shares	588,000
Units granted (in shares) \| shares	171,871
Units vested (in shares) \| shares	(154,141)
Units forfeited (in shares) \| shares	(10,950)
Unvested units, end of period (in shares) \| shares	594,780
Weighted Average Grant Date Fair Value Related to Share-based Compensation
Unvested units, beginning of period (in dollars per share) \| $ / shares	$ 20.98
Units granted (in dollars per share) \| $ / shares	7.59
Units vested (in dollars per share) \| $ / shares	29.04
Units forfeited (in dollars per share) \| $ / shares	20.92
Unvested units, end of period (in dollars per share) \| $ / shares	$ 15.02
Restricted Stock Units
Summary of Activity Related to Share-based Compensation
Unvested units, beginning of period (in shares) \| shares	2,734,475
Units granted (in shares) \| shares	600,712
Units vested (in shares) \| shares	(646,444)
Units forfeited (in shares) \| shares	(119,870)
Unvested units, end of period (in shares) \| shares	2,568,873
Weighted Average Grant Date Fair Value Related to Share-based Compensation
Unvested units, beginning of period (in dollars per share) \| $ / shares	$ 23.21
Units granted (in dollars per share) \| $ / shares	9.86
Units vested (in dollars per share) \| $ / shares	24.50
Units forfeited (in dollars per share) \| $ / shares	18.80
Unvested units, end of period (in dollars per share) \| $ / shares	$ 19.50

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(3)
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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).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
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- Definition

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).

+ References

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- Definition

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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
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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.

+ References

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ References

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