Balance Sheet Components - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2014	Dec. 31, 2013
Balance Sheet Components [Line Items]
Construction of facility liability	$ 19.2		$ 19.2		$ 19.2
Interest expense capitalized	3.7	0.4	6.9	2.3
Depreciation and amortization expense	40.2	21.2	105.1	58.8
Total property and equipment assets under capital lease	32.2		32.2			23.3
Accumulated depreciation related to assets under capital lease	10.7		10.7			5.0
Gigafactory [Member]
Balance Sheet Components [Line Items]
Costs related to construction activities	$ 18.8		$ 18.8