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Long-Term Debt (Details) - USD ($) | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2018 | Aug. 31, 2018 | Dec. 31, 2017 | Jul. 06, 2017 | Nov. 01, 2016 | Dec. 31, 2014 | Nov. 11, 2013
Debt Instrument [Line Items] |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  | $ 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 Instrument, Covenant minimum tangible net worth | 250,000,000.0 |  |  |  |  |  |
Long-term Line of Credit | 0 |  | $ 0 |  |  |  |
Long-term Debt |  |  |  | $ 17,404,000 |  |  |
Letters of Credit Outstanding on a Line of Credit, Amount Outstanding | 10,700,000 |  | 3,700,000 |  |  |  |
Line of Credit Facility, Remaining Borrowing Capacity | $ 89,300,000 |  | $ 171,300,000 |  |  |  |
Prime Rate [Member] |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 0.00% |  |  |  |  |  |
Accordion Feature [Member] |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity | $ 100,000,000.0 |  |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Line of Credit Facility, 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% |  |  |  |  |  |
Minimum [Member] |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Line of Credit Facility, 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% |  |  |  |  |  |

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- References No definition available. + Details
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- Definition letters of credit outstanding on a line of credit + References No definition available. + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + 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(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used. + References No definition available. + Details
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: 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(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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