Long-Term Debt (Notes)	12 Months Ended
Dec. 31, 2017
Debt Disclosure [Abstract]
Line of Credit and Long Term Debt	Long-Term Debt In November 2013, we entered into a Credit Agreement with Wells Fargo Bank, National Association, (the “Bank”). Pursuant to the Credit Agreement, the Bank provided a five-year, $250.0 million unsecured revolving line of credit, which was used to assist in the repayment of all debt acquired at the time of acquisition, and which may be used for future working capital, equipment financing, and general corporate purposes. The Bank's commitment decreased to $175.0 million on November 1, 2016 through October 31, 2018. The Credit Agreement is unsecured, with a negative pledge against all assets of our consolidated group, except for debt associated with permitted acquisitions, new purchase-money debt and capital lease obligations as described in the Credit Agreement. The Credit Agreement matures on October 31, 2018, and may be terminated without penalty. Borrowings under the Credit Agreement can either be, at the Borrower's election, (i) one-month or three-month LIBOR (Index) plus 0.625%, floating, or (ii) Prime (Index) plus 0%, floating. The weighted average variable annual percentage rate is not calculated since no amounts were borrowed and outstanding at December 31, 2017. There is a commitment fee on the unused portion of the line of credit under the Credit Agreement at 0.0625%, due monthly. The Credit Agreement contains customary financial covenants measured quarterly including, but not limited to, (i) a maximum adjusted leverage ratio of 2:1, (ii) required minimum net income of $1.00, and (iii) required minimum tangible net worth of $175.0 million. The Credit Agreement also includes customary events of default, covenants, representations and warranties, and indemnification provisions. We were in compliance with the respective financial covenants at December 31, 2017. We had no long term debt outstanding at December 31, 2017 or 2016. Debt acquired during the acquisition of IDC on July 6, 2017 was repaid prior to September 30, 2017. Outstanding letters of credit associated with the revolving line of credit at December 31, 2017 were $3.7 million compared to $5.5 million at December 31, 2016. As of December 31, 2017, availability for future borrowing under the Credit Agreement was $171.3 million compared to $169.5 million at December 31, 2016.

Long-Term Debt

In November 2013, we entered into a Credit Agreement with Wells Fargo Bank, National Association, (the “Bank”). Pursuant to the Credit Agreement, the Bank provided a five-year, $250.0 million unsecured revolving line of credit, which was used to assist in the repayment of all debt acquired at the time of acquisition, and which may be used for future working capital, equipment financing, and general corporate purposes. The Bank's commitment decreased to $175.0 million on November 1, 2016 through October 31, 2018.

The Credit Agreement is unsecured, with a negative pledge against all assets of our consolidated group, except for debt associated with permitted acquisitions, new purchase-money debt and capital lease obligations as described in the Credit Agreement. The Credit Agreement matures on October 31, 2018, and may be terminated without penalty. Borrowings under the Credit Agreement can either be, at the Borrower's election, (i) one-month or three-month LIBOR (Index) plus 0.625%, floating, or (ii) Prime (Index) plus 0%, floating. The weighted average variable annual percentage rate is not calculated since no amounts were borrowed and outstanding at December 31, 2017. There is a commitment fee on the unused portion of the line of credit under the Credit Agreement at 0.0625%, due monthly.

The Credit Agreement contains customary financial covenants measured quarterly including, but not limited to, (i) a maximum adjusted leverage ratio of 2:1, (ii) required minimum net income of $1.00, and (iii) required minimum tangible net worth of $175.0 million. The Credit Agreement also includes customary events of default, covenants, representations and warranties, and indemnification provisions. We were in compliance with the respective financial covenants at December 31, 2017.

We had no long term debt outstanding at December 31, 2017 or 2016. Debt acquired during the acquisition of IDC on July 6, 2017 was repaid prior to September 30, 2017. Outstanding letters of credit associated with the revolving line of credit at December 31, 2017 were $3.7 million compared to $5.5 million at December 31, 2016. As of December 31, 2017, availability for future borrowing under the Credit Agreement was $171.3 million compared to $169.5 million at December 31, 2016.