Cash and Investments in Marketable Securities [Line Items]

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- Definition

Debt investment maturity date description.

+ References

No definition available.

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- Definition

Debt investment maximum maturity period.

+ References

No definition available.

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- Definition

Long term investment maturity period.

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No definition available.

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- Definition

Minimum cash and investments in marketable securities to be maintained.

+ References

No definition available.

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- Definition

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

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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-Publisher FASB
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- Definition

Description of debt redemption features under terms of the debt agreement.

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- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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- Definition

Fair value portion of notes payable.

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- Definition

Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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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.

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Cash and Investments in Marketable Securities - Additional Information (Detail) - USD ($)				3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Oct. 05, 2015	Mar. 31, 2019	Mar. 31, 2018
Cash and Investments in Marketable Securities [Line Items]
Maximum maturity term for debt securities investment				Two years or less
Weighted average maturity term for debt securities investment				One year or less
Available-for-sale securities, sold				$ 0	$ 11,963,000
Senior secured notes, maturity date				Oct. 05, 2020
Level 1 to level 2 transfers	$ 0			$ 0	0
Level 2 to level 1 transfers	0			0	$ 0
Senior secured notes, principal amount	$ 250,000,000			$ 250,000,000
Senior Notes [Member] \| Level 3 [Member]
Cash and Investments in Marketable Securities [Line Items]
Debt instrument redemption terms				We may redeem some or all of these notes at a redemption price equal to 102% of the principal amount of the notes if the redemption date is prior to October 5, 2019, or 100% of the principal amount of the notes if the redemption date is on or after October 5, 2019, plus, in each case, accrued and unpaid interest to the applicable redemption date.
Senior Notes [Member] \| 7.75% Senior Secured Notes Due October 2020 [Member]
Cash and Investments in Marketable Securities [Line Items]
Senior secured notes, interest rate			7.75%
Senior secured notes, maturity date			Oct. 05, 2020
Minimum cash and investments in marketable securities to be maintained			$ 60,000,000
Senior Notes [Member] \| 7.75% Senior Secured Notes Due October 2020 [Member] \| Level 3 [Member]
Cash and Investments in Marketable Securities [Line Items]
Senior secured notes, interest rate	7.75%			7.75%
Senior secured notes, maturity date				Oct. 05, 2020
Senior secured notes, principal amount	$ 250,000,000			$ 250,000,000
Senior notes, fair value	$ 257,200,000			$ 257,200,000
Senior Notes [Member] \| 7.75% Senior Secured Notes Redemption Date Before October 5, 2019 [Member] \| Level 3 [Member]
Cash and Investments in Marketable Securities [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] \| Level 3 [Member]
Cash and Investments in Marketable Securities [Line Items]
Debt redemption price percentage of principal amount				100.00%
Minimum [Member]
Cash and Investments in Marketable Securities [Line Items]
Long term investment maturity period	1 year	1 year
Maximum [Member]
Cash and Investments in Marketable Securities [Line Items]
Long term investment maturity period	2 years	2 years