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Long-Term Debt (Details) - USD ($) | 9 Months Ended |  |
--- | --- | --- | ---
Sep. 30, 2018 | Nov. 01, 2016 | Dec. 31, 2014
Debt Instrument [Line Items] |  |  |
Line of Credit Facility, Maximum Borrowing Capacity, Current | $ 100,000,000.0 | $ 175,000,000.0 | $ 250,000,000.0
Allowable Amount For Issuance of Letters of Credit | $ 30,000,000.0 |  | $ 20,000,000.0
Debt Instrument, Covenant, Leverage Ratio | 2 |  |
Debt Covenant, Minimum Net Income Requirement | $ 1.00 |  |
Debt Covenant, Minimum Tangible Net Worth | 250,000,000.0 |  |
Letters of Credit Outstanding, Amount | 9,200,000 |  |
Line of Credit Facility, Current Borrowing Capacity | $ 90,800,000 |  |
Prime Rate [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Debt Instrument, Basis Spread on Variable Rate | 0.00% |  |
Minimum [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.0725% |  |
Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Debt Instrument, Basis Spread on Variable Rate | 0.70% |  |
Maximum [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage | 0.175% |  |
Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Debt Instrument, Basis Spread on Variable Rate | 0.90% |  |
Accordion Feature [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Line of Credit Facility, Maximum Borrowing Capacity, Current | $ 100,000,000.0 |  |

X
- Definition Allowable amount for issuance of letters of credit under the credit facility. + References No definition available. + Details
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X
- Definition Debt Covenant, Minimum Net Income Requirement + References No definition available. + Details
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- Definition Debt Instrument, Covenant, Leverage Ratio + References No definition available. + Details
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- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
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- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
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X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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