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Long-Term Debt (Narrative) (Details) | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2019 USD ($) covenant | Jan. 24, 2019 USD ($) | Dec. 31, 2018 USD ($) | Mar. 31, 2013 | Jan. 31, 2013 USD ($)
Debt Instrument [Line Items] |  |  |  |  |
Carrying value of outstanding debt | $ 0 |  | $ 210,400,000 |  |
Unamortized debt issuance costs |  |  | 1,600,000 |  |
Current maturities of long-term debt | 0 |  | 208,805,000 |  |
Senior Subordinated Notes [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, issued value |  |  | $ 210,000,000.0 |  |
Senior Subordinated Notes, interest rate |  |  | 6.25% |  |
Other Debt Obligations [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Carrying value of outstanding debt |  |  | $ 2,000,000.0 |  |
Senior Subordinated 6.25% Notes |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Carrying value of outstanding debt |  |  | $ 210,000,000 |  |
Debt instrument, issued value |  |  |  |  | $ 210,000,000
Senior Subordinated Notes, interest rate |  |  | 6.25% | 6.25% |
Write off of deferred debt issuance cost | 1,100,000 |  |  |  |
Revolving Credit Facility | Senior Credit Agreement |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Revolving credit facility, availability amount | 394,000,000.0 |  |  |  |
Borrowings outstanding | 0 |  | $ 0 |  |
Standby Letters of Credit | Senior Credit Agreement |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Letters of credit issued | $ 6,000,000.0 |  |  |  |
Line of Credit | 2019 Senior Credit Agreement |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Current borrowing capacity |  | $ 400,000,000 |  |  |
Letters of credit issued |  | 700,000,000 |  |  |
Number of debt covenants | covenant | 3 |  |  |  |
Medium-term Notes | 2019 Senior Credit Agreement |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt instrument, issued value |  | $ 300,000,000 |  |  |

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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt 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(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + 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=119400593&loc=d3e572229-122910 + 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=119400593&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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