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Line of Credit | 12 Months Ended
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Dec. 31, 2017
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Line of Credit |
8. | Line of Credit
The Company has an agreement providing for a line of credit in the maximum amount of $20.0 million with Frost Bank. The agreement expires in December 2019. Under the agreement, advances may be made either in the form of loans or letters of credit. Borrowings under the agreement accrue at interest rates based upon prime rate or LIBOR. Under the agreement, the Company pays a fee of 0.25% on the unused portion of the loan in arrears quarterly, or a fee of $50,000 annually, assuming the line of credit is not used during the calendar year. The line of credit is unsecured. No borrowings or letters of credit were outstanding under the line of credit arrangement at December 31, 2017 or 2016.

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