Composition of Certain Financial Statement Captions - Changes in Allowance for Doubtful Accounts, Provision for Inventory Reserve and Tax Valuation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts
Allowance for doubtful accounts for inventory reserve and tax valuation
Beginning balance	$ (1,671)	$ (1,946)
Charged to expense	(891)	(932)
Written-off	1,063	1,110
Charged to other	53	97
Ending balance	(1,446)	(1,671)
Inventory reserve
Allowance for doubtful accounts for inventory reserve and tax valuation
Beginning balance	(945)	(1,051)
Charged to expense	(5,390)	(20)
Written-off	(230)	296
Charged to other	0	(170)
Ending balance	(6,565)	(945)
Tax valuation allowance
Allowance for doubtful accounts for inventory reserve and tax valuation
Beginning balance	(55,415)	(42,147)
Charged to expense	(82,358)	7,726
Written-off	0	0
Charged to other	(4,289)	(20,994)
Ending balance	$ (142,062)	$ (55,415)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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- Definition

Amount of increase in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from charges to costs and expenses.

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- Definition

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- Definition

Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

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