Balance Sheet Components - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	$ 845,254	$ 679,617	$ 554,341
Other comprehensive income (loss) before reclassifications	3,924	1,976
Amounts reclassified from other comprehensive income (loss), net of tax	0	(568)
Other comprehensive income (loss)	3,924	1,408	(4,741)
Balance	967,503	845,254	679,617
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(9,446)	(11,274)
Other comprehensive income (loss) before reclassifications	3,924	1,828
Amounts reclassified from other comprehensive income (loss), net of tax	0	0
Other comprehensive income (loss)	3,924	1,828
Balance	(5,522)	(9,446)	(11,274)
Unrealized gain (loss) on interest rate swap hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	0	420
Other comprehensive income (loss) before reclassifications	0	148
Amounts reclassified from other comprehensive income (loss), net of tax	0	(568)
Other comprehensive income (loss)	0	(420)
Balance	0	0	420
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(9,446)	(10,854)	(6,113)
Other comprehensive income (loss)	3,924	1,408	(4,741)
Balance	$ (5,522)	$ (9,446)	$ (10,854)