Available for sale debt securities remaining maturities greater than three years.

No definition available.

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- Definition

Carrying value as of the balance sheet date of equity securities which are non marketable.

+ References

No definition available.

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- Definition

Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
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- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

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

Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

+ References

No definition available.

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- Definition

Amount of unrealized gain (loss) on investment in marketable security.

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- Definition

Amount before tax and reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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

Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings and other comprehensive loss (OCI).

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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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Marketable Securities - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
Marketable Securities - Additional Information (Detail)	Sep. 30, 2019 USD ($) Security	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Security	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Available for sale debt securities remaining maturities greater than three years	$ 0		$ 0		$ 0
Unrealized gains (losses) on available-for-sale debt securities, before tax	(100,000)	$ 100,000	1,700,000	$ 200,000
Unrealized gains (losses) on available-for-sale debt securities, income tax benefit (expense)	$ 100,000	0	$ (600,000)	0
Number of investment grade fixed income debt security \| Security	7		7
Other-than-temporary impaired			$ 0		$ 0
Non-marketable equity securities, carrying value	$ 400,000		400,000
Marketable securities realized			0
Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Marketable securities unrealized gain (loss)	(2,200,000)		29,400,000
Maximum [Member]
Schedule Of Available For Sale Securities [Line Items]
Unrealized gains (losses) on available-for-sale debt securities, income tax benefit (expense)	100,000		(600,000)
Investment Income [Member] \| Maximum [Member]
Schedule Of Available For Sale Securities [Line Items]
Net realized gains or losses available for sale debt securities	$ 100,000	$ 100,000	$ 100,000	$ 100,000