Balance Sheet Components - Allowance for Doubtful Accounts and Reserve for Subscriber Refunds (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of the year	$ 6,940	$ 6,431	$ 7,450
Additions — charged to costs and expenses, or contra revenue, net	895	816	(586)
Balance at end of year	7,168	6,940	6,431
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of the year	384	444	436
Additions — charged to costs and expenses, or contra revenue, net	107	295	170
Deductions — recoveries of amounts previously charged-off	(89)	(179)	(118)
Deductions — write-offs	(107)	(176)	(44)
Balance at end of year	295	384	444
Reserve for member refunds
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of the year	530	799	813
Additions — charged to costs and expenses, or contra revenue, net	507	776	1,299
Deductions — recoveries of amounts previously charged-off	0	0	0
Deductions — write-offs	(563)	(1,045)	(1,313)
Balance at end of year	$ 474	$ 530	$ 799