Balance Sheet Components - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 554,341
Other comprehensive income (loss) before reclassifications	$ (817)	$ 1,424	(2,163)	$ 3,499
Amounts reclassified from other comprehensive income (loss), net of tax	(324)	(109)	(808)	(156)
Net current-period other comprehensive income (loss), net of tax	(1,141)	1,315	(2,971)	3,343
Unrealized losses on interest rate swap contracts	(234)	(74)	(122)	(45)
Ending balance	619,239		619,239
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(8,896)	(8,765)	(6,954)	(10,764)
Other comprehensive income (loss) before reclassifications	(907)	1,389	(2,849)	3,388
Amounts reclassified from other comprehensive income (loss), net of tax	0	0	0	0
Net current-period other comprehensive income (loss), net of tax	(907)	1,389	(2,849)	3,388
Ending balance	(9,803)	(7,376)	(9,803)	(7,376)
Unrealized gain (loss) on interest rate swap hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	953	1,274	841	1,245
Other comprehensive income (loss) before reclassifications	90	35	686	111
Amounts reclassified from other comprehensive income (loss), net of tax	(324)	(109)	(808)	(156)
Net current-period other comprehensive income (loss), net of tax	(234)	(74)	(122)	(45)
Ending balance	719	1,200	719	1,200
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(7,943)	(7,491)	(6,113)	(9,519)
Ending balance	$ (9,084)	$ (6,176)	$ (9,084)	$ (6,176)

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

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Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Amount before tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount before tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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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.

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