Employee Benefits and Stock Compensation - Employee Stock Purchase Plan (Details) - ESPP - $ / shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	19,713	16,320	15,225
Weighted-average employee purchase price (in dollars per share)	$ 20.68	$ 25.39	$ 26.85

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.

No definition available.

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