XML 51 R40.htm IDEA: XBRL DOCUMENT v3.8.0.1

Cash Equivalents and Marketable Debt Securities - Available-for-Sale Investments in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	$ 85,884	$ 78,808
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(220)	(124)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	37,799	49,519
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	(335)	(262)
Government Sponsored Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	1,999	9,744
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(7)	(20)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	13,191	12,205
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	(70)	(51)
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	73,914	67,522
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(208)	(104)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	23,211	35,918
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	(262)	(206)
Foreign Government Bonds
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	4,533	1,542
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(2)	0
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	1,397	1,396
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	(3)	$ (5)
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	5,438
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(3)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	0
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	$ 0

X

- Definition

Amount of unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount of unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

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.

+ Details

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=us-gaap_AgencySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ForeignGovernmentDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: