v3.4.0.3

Investments - Components of Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	$ 303,905	$ 303,029
Unrealized Gains	102
Unrealized Losses	(198)	(876)
Fair Value	303,809	302,153
Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	301,571	300,735
Unrealized Gains	102
Unrealized Losses	(198)	(876)
Fair Value	301,475	299,859
Investments [Member] | Money Market Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	17,877	18,181
Fair Value	17,877	18,181
Investments [Member] | Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	5,994	5,986
Unrealized Gains	1
Unrealized Losses		(5)
Fair Value	5,995	5,981
Investments [Member] | US Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	27,301	11,499
Unrealized Gains	7
Unrealized Losses	(6)	(30)
Fair Value	27,302	11,469
Investments [Member] | Corporate Bonds and Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	250,399	265,069
Unrealized Gains	94
Unrealized Losses	(192)	(841)
Fair Value	250,301	264,228
Deferred Compensation Plan Assets [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost Basis	2,334	2,294
Fair Value	$ 2,334	$ 2,294

X

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
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- Definition

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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+ 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 210.5-02.2)
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