Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes the activity for all stock options under the Company’s equity incentive plans for the year ended December 31, 2015 (shares in thousands):

				Weighted		Weighted
				Average		Average
	Options			Exercise Price		Remaining
	Outstanding			Outstanding		Contractual Life
Outstanding at December 31, 2014		11,408		$	4.42		8.20
Granted		3,806			9.50
Exercised		(1,210	)		2.96
Cancelled / forfeited		(1,209	)		6.27
Outstanding at December 31, 2015		12,795		$	5.89		7.82
Options vested and exercisable at    December 31, 2015		6,409		$	3.88		6.80
Options vested and expected to    vest at December 31, 2015		10,460		$	5.69		7.65

Estimated Fair Value of Stock Options

The Company estimated the fair value of stock options with the following assumptions:

	Year Ended December 31,
	2015			2014			2013
Risk-free interest rate	1.55%-1.95%			1.68%-2.01%			0.82%-2.06%
Volatility	36.30%-39.63%			37.41%-46.68%			54.36%-55.80%
Expected term (in years)	5.50-6.23			5.34-6.08			5.54-6.08
Expected dividend yield		0.00	%		0.00	%		0.00	%

Summary of Activity for All RSUs

The following table summarizes the activity for all RSUs under all the Company’s equity incentive plans for the year ended December 31, 2015 (shares in thousands):

				Weighted
				Average Grant
				Date Fair
	Shares			Value
Unvested balance at December 31, 2014		947		$	9.40
Granted		808			11.13
Issued		(182	)		9.58
Cancelled / forfeited		(67	)		11.37
Unvested balance at December 31, 2015		1,506		$	10.44

Summary of Stock-Based Compensation Expense

The Company recognized stock-based compensation expense, including the compensation expense resulting from the sales of common stock by employees and former employees to existing investors and ESPP expenses, in the consolidated statements of operations as follows (in thousands):

	Year Ended December 31,
	2015		2014		2013
Cost of operating leases and incentives	$	1,649	$	155	$	116
Cost of solar energy systems and product sales		236		682		—
Sales and marketing		5,242		897		474
Research and development		205		270		379
General and administration		8,491		7,214		1,686
Total	$	15,823	$	9,218	$	2,655