Stock-based Compensation - Restricted Stock Deferred Stock, and Performance Share Units (Details) - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Weighted average share price, beginning balance (usd per share)	$ 18.50	$ 18.61	$ 16.53
Weighted average shares granted (usd per share)	16.72	18.63	27.05
Weighted average shares vested (usd per share)	15.59	19.61	28.07
Weighted average shares adjustment for incentive awards expected to vest (usd per share)	25.04	24.30	26.93
Weighted average shares canceled and forfeited (usd per share)	20.07	20.79	16.38
Weighted average share price, ending balance (usd per share)	$ 18.05	$ 18.50	$ 18.61
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Nonvested Shares, Outstanding, Beginning Balance (shares)	150,799	191,825	186,806
Granted (shares)	104,789	62,125	62,320
Vested (shares)	(73,260)	(90,282)	(36,876)
Adjustment for incentive awards expected to vest (shares)	0	0	0
Canceled and forfeited (shares)	(10,394)	(12,869)	(20,425)
Nonvested Shares, Outstanding, Ending Balance (shares)	171,934	150,799	191,825
Deferred Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Nonvested Shares, Outstanding, Beginning Balance (shares)	54,078	41,774	26,860
Granted (shares)	12,058	12,304	14,914
Vested (shares)	0	0	0
Adjustment for incentive awards expected to vest (shares)	0	0	0
Canceled and forfeited (shares)	0	0	0
Nonvested Shares, Outstanding, Ending Balance (shares)	66,136	54,078	41,774
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Nonvested Shares, Outstanding, Beginning Balance (shares)	331,148	300,373	181,341
Granted (shares)	105,857	89,092	65,421
Vested (shares)	(163,224)	0	0
Adjustment for incentive awards expected to vest (shares)	(96,364)	(52,180)	65,491
Canceled and forfeited (shares)	(27,395)	(6,137)	(11,880)
Nonvested Shares, Outstanding, Ending Balance (shares)	150,022	331,148	300,373

The number of equity-based payment instruments, excluding stock (or unit) options, that are now expected to vest.

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- Definition

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 award is now expected to vest.

+ References

No definition available.

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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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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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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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-Publisher FASB
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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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