Comprehensive Income (Loss) - Components (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Loss:
Beginning balance	$ (17,777)	$ 78,546	$ 2,780	$ 85,580
Net other comprehensive loss	(8,988)	(15,763)	(30,043)	(31,830)
Ending balance	(26,963)	65,742	(26,963)	65,742
Foreign currency translation adjustment:
Accumulated Other Comprehensive Loss:
Beginning balance	(23,720)	(23,435)	(23,621)	(23,202)
Net other comprehensive loss	(210)	(60)	(309)	(293)
Ending balance	(23,930)	(23,495)	(23,930)	(23,495)
Unrealized gain (loss) on marketable debt securities, net
Accumulated Other Comprehensive Loss:
Beginning balance	872	(224)	205	(64)
Net other comprehensive loss	86	68	753	(92)
Ending balance	958	(156)	958	(156)
Accumulated Other Comprehensive Loss:
Accumulated Other Comprehensive Loss:
Beginning balance	(22,848)	(23,659)	(23,416)	(23,266)
Ending balance	$ (22,972)	$ (23,651)	$ (22,972)	$ (23,651)

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(31))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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