Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

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 years ended December 31, 2016 and 2015 (shares in thousands):

				Weighted		Weighted
				Average		Average		Aggregate
	Options			Exercise Price		Remaining		Intrinsic
	Outstanding			Outstanding		Contractual Life		Value
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	$	75,797
Granted		3,674			5.73
Exercised		(1,852	)		2.94
Cancelled / forfeited		(1,720	)		8.37
Outstanding at December 31, 2016		12,897		$	5.94		7.49	$	9,625
Options vested and exercisable at    December 31, 2016		6,763		$	5.19		6.40	$	8,943
Options vested and expected to    vest at December 31, 2016		10,886		$	5.80		7.25	$	9,435

Estimated Fair Value of Stock Options

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

	Year Ended December 31,
	2016			2015			2014
Risk-free interest rate	1.18% - 2.23%			1.55% - 1.95%			1.68% - 2.01%
Volatility	36.00% - 49.64%			36.30% - 39.63%			37.41% - 46.68%
Expected term (in years)	5.00 - 6.26			5.50 - 6.23			5.34 - 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 of the Company’s equity incentive plans for the years ended December 31, 2016 and 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
Granted		3,363			5.82
Issued		(422	)		9.55
Cancelled / forfeited		(341	)		6.80
Unvested balance at December 31, 2016		4,106		$	6.87

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 in 2015 and 2014 to existing investors and ESPP expenses, in the consolidated statements of operations as follows (in thousands):

	Year Ended December 31,
	2016		2015		2014
Cost of operating leases and incentives	$	2,039	$	1,649	$	155
Cost of solar energy systems and product sales		409		236		682
Sales and marketing		7,831		5,242		897
Research and development		515		205		270
General and administration		7,929		8,491		7,214
Total	$	18,723	$	15,823	$	9,218