BALANCE SHEET COMPONENTS - ADDITIONAL INFORMATION (Details) ft² in Thousands	3 Months Ended		9 Months Ended		12 Months Ended	17 Months Ended
	Sep. 30, 2016 USD ($) term	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) term	Sep. 30, 2015 USD ($)	Dec. 31, 2013 ft²	Sep. 30, 2016 USD ($) term	Dec. 31, 2015 USD ($)
Balance Sheet Components [Abstract]
Depreciation and amortization expense, excluding amortization of capitalized software and intangible assets	$ 1,839,000	$ 1,655,000	$ 5,190,000	$ 4,164,000
Amortized capitalized software development costs	65,000	$ 76,000	220,000	$ 232,000
Net book value of capitalized software development costs	121,000		121,000			$ 121,000	$ 351,000
Office building area (in square feet) | ft²					64
Additional construction cost						0
Financing obligation	$ 15,975,000		$ 15,975,000			$ 15,975,000
Lease term			15 years
Number of renewal terms | term	3		3			3
Renewal term			5 years