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Schedule of Reported Available for Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	$ 469,504	$ 259,011
Available-for-sale marketable securities, Unrealized Gain	3,845	592
Available-for-sale marketable securities, Unrealized (Loss)	(438)	(2,967)
Available-for-sale marketable securities, Fair Market Value	472,911	256,636
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	38,277	191,978
Marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	399,852	190,100
Available-for-sale marketable securities, Unrealized Gain	391	88
Available-for-sale marketable securities, Unrealized (Loss)	(16)	(92)
Available-for-sale marketable securities, Fair Market Value	400,227	190,096
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	21,708	140,262
Long-term marketable securities
Schedule of Available-for-sale Securities
Available-for-sale marketable securities, Cost	69,652	68,911
Available-for-sale marketable securities, Unrealized Gain	3,454	504
Available-for-sale marketable securities, Unrealized (Loss)	(422)	(2,875)
Available-for-sale marketable securities, Fair Market Value	72,684	66,540
Available-for-sale marketable securities, Fair Market Value of Investments with Unrealized Losses	$ 16,569	$ 51,716

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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