Long-Term Obligations Senior Notes Narrative (Details) - Senior Notes - 2025 Notes - USD ($)	May 23, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Debt instrument, face amount	$ 250,000,000.0
Debt instrument, interest rate, stated percentage	6.75%	6.75%
Debt instrument, redemption price, percentage of principal amount redeemed	35.00%
Line of credit facility, amount outstanding		$ 250,000,000
Deferred financing costs		(5,500,000)
Debt discount		$ (1,700,000)
Prior to May 15, 2020
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage of principal amount redeemed	106.75%
Twelve-Month Period Beginning on May 15, 2020
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage of principal amount redeemed	105.063%
Twelve-Month Period Beginning on May 15, 2021
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage of principal amount redeemed	103.375%
Twelve-Month Period Beginning on May 15, 2022
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage of principal amount redeemed	101.688%
Twelve-Month Period Beginning on May 15, 2023
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage of principal amount redeemed	100.00%

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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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://www.xbrl.org/2003/role/presentationRef
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