Benefit Plans - Share Option Activity (Details) - Share Options - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of shares outstanding, beginning (in shares)	118,400	134,790
Number of shares exercised (in shares)	(84,400)	(16,390)
Number of shares outstanding, ending (in shares)	34,000	118,400
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Price per share outstanding, beginning (usd per share)	$ 7.44	$ 7.39
Price per share exercised (usd per share)	7.24	6.99
Price per share outstanding, ending (usd per share)	$ 7.95	$ 7.44

Number of options outstanding, including both vested and non-vested options.

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Number of share options (or share units) exercised during the current period.

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