Stock-Based Compensation - Summary of Performance Share Award Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Performance awards
Shares
Outstanding, beginning of period (in shares)	138,245	112,253	126,975
Granted at target (in shares)	79,788	72,932	66,764
Forfeited (in shares)	4,396	1,505	9,247
Vested (in shares)	(78,260)	(8,854)	(29,655)
Outstanding, end of period (in shares)	150,339	138,245	112,253
Per Share Weighted-Average Grant Date Fair Value
Outstanding, beginning of period (in dollars per share)	$ 37.02	$ 39.73	$ 35.29
Granted at target (in dollars per share)	34.10	39.26	34.52
Forfeited (in dollars per share)	36.28	43.43	30.85
Vested (in dollars per share)	48.86	58.34	33.35
Outstanding, end of period (in dollars per share)	$ 36.54	$ 37.02	$ 39.73
Forfeited for performance below target
Shares
Forfeited (in shares)		36,581	42,584
Per Share Weighted-Average Grant Date Fair Value
Forfeited (in dollars per share)		$ 48.94	$ 29.73
Earned for performance above target, net
Shares
Forfeited (in shares)	14,962
Per Share Weighted-Average Grant Date Fair Value
Forfeited (in dollars per share)	$ 69.45

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

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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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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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