Long-term debt: (Details) $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($)
Limitations under the Indentures
Permitted investments and payments	$ 41.5
Permitted investments and payments held by Holdings	$ 40.5
Minimum
Limitations under the Indentures
Consolidated leverage ratio	4.25
Senior unsecured 2021 notes
Limitations under the Indentures
Senior notes outstanding	$ 189.2
Interest rate (as a percent)	5.625%
Senior secured 2022 notes
Limitations under the Indentures
Senior notes outstanding	$ 375.0
Interest rate (as a percent)	5.375%
Restriction on incurring additional indebtedness \| Minimum
Limitations under the Indentures
Consolidated leverage ratio	5.0
Restriction on certain payments \| Minimum
Limitations under the Indentures
Consolidated leverage ratio	4.25
Increase in unrestricted payment amount \| Maximum
Limitations under the Indentures
Consolidated leverage ratio	4.25

Represents the amount of permitted investments and payments.

No definition available.

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- Definition

Represents the amount of permitted investments held by Holdings.

+ References

No definition available.

+ Details

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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

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- Definition

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

+ References

+ Details

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- References

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- Definition

Indebtedness divided by net capital.

+ References

No definition available.

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