Equity Incentive Plan - Performance share activity (Details) - $ / shares shares in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance shares paid out maximum	150.00%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Outstanding, granted	47
Shares Outstanding, vested	(16)
Shares Outstanding, at end of the period	31
Weighted Average Grant Date Fair Value, granted (in dollars per share)	$ 47.73
Weighted Average Grant Date Fair Value, vested (in dollars per share)	$ 47.73
Weighted Average Grant Date Fair Value, at end of the period (in dollars per share)		$ 47.73
Vesting period	3 years
Performance Units And Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Outstanding, at beginning of the period	87
Shares Outstanding, granted	42
Shares Outstanding, vested	(31)
Shares Outstanding, forfeited	(3)
Shares Outstanding, at end of the period	95
Weighted Average Grant Date Fair Value, at beginning of the period (in dollars per share)	$ 69.61
Weighted Average Grant Date Fair Value, granted (in dollars per share)	63.42
Weighted Average Grant Date Fair Value, vested (in dollars per share)	47.73
Weighted Average Grant Date Fair Value, forfeited (in dollars per share)	90.17
Weighted Average Grant Date Fair Value, at end of the period (in dollars per share)	$ 69.61	$ 63.35
Vesting period	3 years

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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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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.

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

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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.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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