Related Party Transactions - Exchange Agreements (Details) - Castle Creek Capital Partners V, LP	12 Months Ended
Dec. 31, 2018 shares
Nonvoting Common Stock
Related-Party Transactions
Stock Repurchases (in shares)	1,431,796
Voting Common Stock
Related-Party Transactions
Number of shares issued	1,431,796

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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