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Senior Secured Notes - Additional Information (Detail) - USD ($) |  | 12 Months Ended
--- | --- | ---
Oct. 05, 2015 | Dec. 31, 2018
Secured Notes [Line Items] |  |
Senior secured notes, principal amount |  | $ 250,000,000
Actual days outstanding |  | 360 days
Senior secured notes, maturity date |  | Oct. 05, 2020
Senior Notes [Member] | 7.75% Senior Secured Notes Due October 2020 [Member] |  |
Secured Notes [Line Items] |  |
Senior secured notes, principal amount | $ 250,000,000 |
Senior secured notes, interest rate | 7.75% |
Senior secured notes, maturity date | Oct. 05, 2020 |
Frequency of payment |  | Quarterly
Issuance costs | $ 8,900,000 |
Debt discount on transaction and facility fees | 8,700,000 |
Unamortized debt discount and issuance costs |  | $ 3,100,000
Minimum cash and investments in marketable securities to be maintained | $ 60,000,000 |
Percentage of repurchase of notes on principal amount of notes | 101.00% |
Percentage of repurchase of notes on principal amount of notes upon sale of assets | 100.00% |
Senior Notes [Member] | 7.75% Senior Secured Notes Due October 2020 [Member] | Level 3 [Member] |  |
Secured Notes [Line Items] |  |
Senior notes fair value |  | $ 258,000,000
Senior Notes [Member] | 7.75% Senior Secured Notes Redemption Date Before October 5, 2019 [Member] |  |
Secured Notes [Line Items] |  |
Debt redemption price percentage of principal amount | 102.00% |
Senior Notes [Member] | 7.75% Senior Secured Notes Redemption Date After October 5, 2019 [Member] |  |
Secured Notes [Line Items] |  |
Debt redemption price percentage of principal amount | 100.00% |

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- Definition Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders. + References Reference 1: 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(a)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 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 + Details
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