Balance Sheet Components - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 554,341
Other comprehensive income (loss) before reclassifications	$ (4,219)	$ 976	(1,346)	$ 2,075
Amounts reclassified from other comprehensive income (loss), net of tax	(285)	(53)	(484)	(47)
Net current-period other comprehensive income (loss), net of tax	(4,504)	923	(1,830)	2,028
Unrealized gains (losses) on interest rate swap contracts	(90)	(153)	112	29
Ending balance	588,640		588,640
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,482)	(9,841)	(6,954)	(10,764)
Other comprehensive income (loss) before reclassifications	(4,414)	1,076	(1,942)	1,999
Amounts reclassified from other comprehensive income (loss), net of tax	0	0	0	0
Net current-period other comprehensive income (loss), net of tax	(4,414)	1,076	(1,942)	1,999
Ending balance	(8,896)	(8,765)	(8,896)	(8,765)
Unrealized gain (loss) on interest rate swap hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,043	1,427	841	1,245
Other comprehensive income (loss) before reclassifications	195	(100)	596	76
Amounts reclassified from other comprehensive income (loss), net of tax	(285)	(53)	(484)	(47)
Net current-period other comprehensive income (loss), net of tax	(90)	(153)	112	29
Ending balance	953	1,274	953	1,274
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,439)	(8,414)	(6,113)	(9,519)
Ending balance	$ (7,943)	$ (7,491)	$ (7,943)	$ (7,491)

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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