Castlight Health (CSLT) 10-Q 5 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 31, 2015
Class of Stock [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Trading Symbol	CSLT
Entity Registrant Name	CASTLIGHT HEALTH, INC.
Entity Central Index Key	1,433,714
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Class A [Member]
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		54,681,184
Class B [Member]
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		39,635,427

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 31,533	$ 17,425
Marketable securities	132,905	175,057
Accounts receivable, net	11,048	11,097
Deferred commissions	3,956	3,675
Prepaid expenses and other current assets	5,960	3,476
Total current assets	185,402	210,730
Property and equipment, net	4,515	3,630
Marketable securities, noncurrent	0	6,220
Restricted cash, noncurrent	1,000	0
Deferred commissions, noncurrent	2,374	2,563
Other assets	3,692	131
Total assets	196,983	223,274
Current liabilities:
Accounts payable	4,180	3,217
Accrued expenses and other current liabilities	4,702	5,791
Accrued compensation	8,730	10,455
Deferred revenue	24,125	20,708
Total current liabilities	41,737	40,171
Deferred revenue, noncurrent	7,638	6,652
Other liabilities, noncurrent	1,208	261
Total liabilities	$ 50,583	$ 47,084
Commitments and contingencies
Stockholders’ equity (deficit):
Additional paid-in capital	$ 404,412	$ 393,397
Accumulated other comprehensive income	10	(40)
Accumulated deficit	(258,031)	(217,176)
Total stockholders’ equity (deficit)	146,400	176,190
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	196,983	223,274
Class A [Member]
Stockholders’ equity (deficit):
Common stock value issued	5	6
Class B [Member]
Stockholders’ equity (deficit):
Common stock value issued	$ 4	$ 3

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue:
Subscription		$ 17,278	$ 9,576	$ 32,184	$ 17,039
Professional services		1,232	957	2,277	1,870
Total revenue		18,510	10,533	34,461	18,909
Cost of revenue:
Cost of subscription	[1]	2,932	2,915	5,451	5,627
Cost of professional services	[1]	5,322	4,502	9,975	8,373
Total cost of revenue		8,254	7,417	15,426	14,000
Gross profit		10,256	3,116	19,035	4,909
Operating expenses:
Sales and marketing	[1]	17,641	14,947	34,104	31,507
Research and development	[1]	7,391	5,476	13,985	11,003
General and administrative	[1]	6,517	4,519	11,980	8,529
Total operating expenses		31,549	24,942	60,069	51,039
Operating loss		(21,293)	(21,826)	(41,034)	(46,130)
Other income, net		81	50	179	73
Net loss		$ (21,212)	$ (21,776)	$ (40,855)	$ (46,057)
Net loss per Class A and B share, basic and diluted		$ (0.23)	$ (0.24)	$ 0	$ 0
Weighted-average shares used to compute basic and diluted net loss per Class A and B share		93,804	89,520	92,801	53,284
[1]	Includes stock-based compensation expense as follows: Cost of subscription $67 and $35. Cost of professional services $450 and $280. Sales and marketing $2,074 and $1,152. Research and development $730 and $493. General and administrative $896 and $980

Consolidated Statements of Ope4

Consolidated Statements of Operations Parenthetical - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Cost of subscription [Member]
Allocated Share-based Compensation Expense	$ 67	$ 35	$ 100	$ 39
Cost of professional services [Member]
Allocated Share-based Compensation Expense	450	280	875	420
Sales and marketing [Member]
Allocated Share-based Compensation Expense	2,074	1,152	3,825	2,326
Research and development [Member]
Allocated Share-based Compensation Expense	730	493	1,363	914
General and administrative [Member]
Allocated Share-based Compensation Expense	$ 896	$ 980	$ 1,923	$ 1,794

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Consolidated Statement of Comprehensive Loss:
Net loss	$ (21,212)	$ (21,776)	$ (40,855)	$ (46,057)
Other comprehensive income (loss):
Net change in unrealized gain (loss) on available-for-sale marketable securities	8	(41)	50	(40)
Reclassification adjustments for net realized gains on available-for-sale marketable securities	0	0	0	0
Other comprehensive income (loss)	8	(41)	50	(40)
Comprehensive loss	$ (21,204)	$ (21,817)	$ (40,805)	$ (46,097)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities:
Net loss	$ (40,855)	$ (46,057)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	910	604
Stock-based compensation	8,086	5,493
Amortization of deferred commissions	1,659	2,244
Accretion and amortization of marketable securities	827	497
Expense related to warrant	0	2,499
Changes in operating assets and liabilities:
Accounts receivable	49	(5,327)
Deferred commissions	(1,751)	(1,369)
Prepaid expenses and other assets	(1,818)	(1,677)
Accounts payable	1,258	384
Accrued expenses and other liabilities	(3,169)	(1,203)
Deferred revenue	4,403	8,277
Net cash used in operating activities	(30,401)	(35,635)
Investing activities:
Restricted cash	(1,000)	101
Purchase of property and equipment	(1,693)	(967)
Investment in related party	3,125	0
Purchase of marketable securities	(18,958)	(162,175)
Sales of marketable securities	5,000	13,000
Maturities of marketable securities	61,553	8,000
Net cash provided by (used in) investing activities	41,777	(142,041)
Financing activities:
Proceeds from the exercise of stock options	2,826	1,628
Payments of deferred offering costs	0	189,943
Payments of deferred offering costs	(94)	(3,781)
Net cash provided by financing activities	2,732	187,790
Net increase in cash and cash equivalents	14,108	10,114
Cash and cash equivalents at beginning of period	17,425	25,154
Cash and cash equivalents at end of period	$ 31,533	$ 35,268

Organization and Description of

Organization and Description of Business	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Description of Business Castlight Health, Inc. ("Castlight") is a pioneer in a new category of cloud-based software that enables enterprises to understand and manage health care spending as a strategic business investment, and help employees and their families make more informed medical decisions based on factors such as cost, quality and patient experience. Our Enterprise Healthcare Management solutions allow our customers to conquer the complexity of the existing health care system by providing personalized, actionable information to their employees, implementing technology-enabled benefit designs and integrating disparate systems and applications. Our comprehensive technology offering aggregates complex, large-scale data and applies sophisticated analytics to make health care data transparent and useful. We were incorporated in the State of Delaware in January 2008. Our principal executive offices are located in San Francisco, California.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (GAAP), for interim financial information and with the instructions to Form 10-Q and Article 10 of Securities and Exchange Commission (SEC), Regulation S-X. In the opinion of management, the information herein reflects all adjustments, consisting only of normal recurring adjustments except as otherwise noted, considered necessary for a fair statement of results of operations, financial position and cash flows. The condensed consolidated financial statements include the results of Castlight and its wholly owned U.S. subsidiary. The results for the interim periods presented are not necessarily indicative of the results expected for any future period. The condensed consolidated balance sheet as of December 31, 2014 included herein was derived from the audited financial statements as of that date. The following information should be read in conjunction with the audited financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2014 . There have been no changes to our significant accounting policies described in our Annual Report on Form 10-K that have had a material impact on our condensed consolidated financial statements and related notes. Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires us to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, as well as the reported amounts of revenue and expenses during the reporting period. These estimates include, but are not limited to, the determination of the relative selling prices for our services, certain assumptions used in the valuation of our equity awards, and the capitalization and estimated useful life of internal-use software development costs. Actual results could differ from those estimates, and such differences could be material to our consolidated financial position and results of operations. Recently Issued and Adopted Accounting Pronouncements In April 2015, the Financial Accounting Standards Board (FASB) issued new accounting guidance Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. This guidance is intended to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement, primarily to determine whether the arrangement includes a sale or license of software. The guidance will be effective for us beginning January 1, 2016 . Early adoption is permitted. We have elected not to early adopt. The adoption of this guidance is not expected to have a material impact on our condensed consolidated financial statements. In May 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09 regarding ASC Topic 606, Revenue from Contracts with Customers. The standard provides principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance will be effective for us beginning January 1, 2018. Early adoption is not permitted. We are evaluating the accounting, transition and disclosure requirements of the standard and cannot currently estimate the financial statement impact of adoption.

Marketable Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities At June 30, 2015 and December 31, 2014 , respectively, marketable securities consisted of the following (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value June 30, 2015 U.S. agency obligations $ 145,414 $ 16 $ (5 ) $ 145,425 Money market mutual funds 8,015 — — 8,015 153,429 16 (5 ) 153,440 Included in cash and cash equivalents 20,535 — — 20,535 Included in marketable securities $ 132,894 $ 16 $ (5 ) $ 132,905 Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2014 U.S. agency obligations $ 177,297 $ 4 $ (44 ) $ 177,257 U.S. treasury securities 5,580 1 — 5,581 Money market mutual funds 1,919 — — 1,919 184,796 5 (44 ) 184,757 Included in cash and cash equivalents 3,480 — — 3,480 Included in marketable securities $ 175,093 $ 5 $ (41 ) $ 175,057 Included in marketable securities, noncurrent $ 6,223 $ — $ (3 ) $ 6,220

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We measure our financial assets and liabilities at fair value at each reporting period using a fair value hierarchy that requires that we maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s classification within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Three levels of inputs may be used to measure fair value: Level 1—Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Include other inputs that are directly or indirectly observable in the marketplace. Level 3—Unobservable inputs that are supported by little or no market activity. The fair value of marketable securities included in the Level 2 category is based on observable inputs, such as quoted prices for similar assets at the measurement date; quoted prices in markets that are not active; or other inputs that are observable, either directly or indirectly. These values were obtained from a third-party pricing service and were evaluated using pricing models that vary by asset class and may incorporate available trade, bid and other market information and price quotes from well-established third party pricing vendors and broker-dealers. There have been no changes in valuation techniques in the periods presented. We have no financial assets or liabilities measured using Level 3 inputs. There were no significant transfers between Levels 1 and 2 assets as of June 30, 2015 and December 31, 2014 . The following tables present information about our assets that are measured at fair value on a recurring basis using the above input categories (in thousands): Level 1 Level 2 Total June 30, 2015 Cash equivalents: Money market mutual funds 8,015 — 8,015 U.S. agency obligations — 12,520 12,520 Marketable securities: U.S. agency obligations — 132,905 132,905 $ 8,015 $ 145,425 $ 153,440 Level 1 Level 2 Total December 31, 2014 Cash equivalents: Money market mutual funds $ 1,919 $ — $ 1,919 U.S. agency obligations — 1,561 1,561 Marketable securities: U.S. agency obligations — 175,696 175,696 U.S. treasury securities — 5,581 5,581 $ 1,919 $ 182,838 $ 184,757 Gross unrealized gains and losses for cash equivalents and marketable securities as of June 30, 2015 and December 31, 2014 were not material. We do not believe the unrealized losses represent other-than-temporary impairments based on our evaluation of available evidence as of June 30, 2015 . There were no realized gains or losses during the three months ended June 30, 2015 . All of our marketable securities at June 30, 2015 mature within one year . As of December 31, 2014 those securities with maturities greater than one year are reflected in the noncurrent portion of our condensed consolidated balance sheets. Marketable securities on the balance sheets consist of securities with original or remaining maturities at the time of purchase of greater than three months, and the remainder of the securities is reflected in cash and cash equivalents.

Property and equipment, net

Property and equipment, net	6 Months Ended
	Jun. 30, 2015
Property, Plant and Equipment [Abstract]
Property and equipment	Property and Equipment Property and equipment consisted of the following (in thousands): As of June 30, 2015 December 31, 2014 Leasehold improvements $ 1,058 $ 1,058 Computer equipment 3,641 3,247 Software 874 874 Capitalization of internal-use software 1,155 291 Furniture and equipment 301 301 Construction in process 537 — Total 7,566 5,771 Accumulated depreciation (3,051 ) (2,141 ) Property and equipment, net $ 4,515 $ 3,630 Depreciation and amortization expense for the three months ended June 30, 2015 and 2014 , was $0.5 million and $0.3 million , respectively , and $ 0.9 million and $ 0.6 million for the six months ended June 30, 2015 and 2014 , respectively. Depreciation is recorded on a straight-line basis.

Related Party Transactions (Not

Related Party Transactions (Notes)	6 Months Ended
	Jun. 30, 2015
Related Party Transactions [Abstract]
Related Party Transactions and Variable Interest Entity	Note 6. Related Party Transactions and Variable Interest Entity In the second quarter of 2015, we announced a strategic alliance with Lyra Health ("Lyra"), to develop and bring to market an integrated behavioral health solution. In connection with this strategic alliance, the Company made a $3.1 million preferred stock investment in Lyra. Lyra is considered a related party to us because two of Lyra’s co-founders serve on our board of directors, and Castlight's Chief Executive Officer, serves on Lyra's board. An independent committee of Castlight's board of directors, comprising of directors with no involvement in any external behavioral health business initiatives, approved the strategic alliance with and investment in Lyra. Lyra Health was founded in 2015 to work with employers, health plans, and providers to improve behavioral health outcomes and plans to offer a complementary behavioral health service that combines technology with active care management to improve patient outcomes. As part of the strategic alliance Lyra's product will be integrated with Castlight Elevate for those customers who purchase the integrated solution. Castlight Elevate is an extension of the Castlight enterprise healthcare management platform which enables employees to research behavioral health services, make educated treatment choices, and commence care. We have evaluated these transactions, including their related party aspects, and have determined that Lyra is a variable interest entity (“VIE”) for Castlight. In determining that we are not the VIE's primary beneficiary, we considered qualitative and quantitative factors, including, but not limited to: which activities most significantly impact the VIE’s economic performance and which party controls such activities; the characteristics of our involvement; and the obligation or likelihood for us to provide incremental financial support. Based on our evaluation, we determined that Castlight and our related parties collectively have power and benefits of the operations of VIE but that we are not the party most closely associated to the VIE. Accordingly, we are not required to consolidate the operations of the VIE. Our maximum exposure to loss as a result of our involvement with this unconsolidated VIE is limited to our investment of $3.1 million and we are not obligated to provide incremental financial support to Lyra. The investment in Lyra is accounted for under the cost method and is included under other assets in our condensed consolidated financial statements. We have not estimated the fair value of our investment because there have been no identified events or changes in circumstances that may have a significant adverse effect on the fair value of the investment. We will assess our investment for impairment on a quarterly basis or based on facts or circumstances that may require us to reassess the fair value of our investment.

Deferred Revenue

Deferred Revenue	6 Months Ended
	Jun. 30, 2015
Deferred Revenue Disclosure [Abstract]
Deferred Revenue	Deferred Revenue Deferred revenue consisted of the following (in thousands): As of June 30, 2015 December 31, 2014 Subscription $ 17,373 $ 14,826 Professional services—implementation 3,622 2,974 Professional services—communications 3,130 2,908 Total current 24,125 20,708 Subscription 2,090 1,950 Professional services—implementation 4,816 4,327 Professional services—communications 732 375 Total noncurrent 7,638 6,652 Total $ 31,763 $ 27,360

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Matters On April 2, April 16, April 29, and May 4, 2015, purported securities class action lawsuits were filed in the Superior Court of the State of California, County of San Mateo, against us, certain of our current and former directors, executive officers, significant stockholders and underwriters associated with our IPO. The lawsuits, which were consolidated on July 22, 2015, were brought by purported stockholders of our company seeking to represent a class consisting of all those who purchased our stock pursuant and/or traceable to the Registration Statement and Prospectus issued in connection with our IPO. The lawsuits assert claims under Sections 11, 12(a)(2) and 15 of the Securities Act of 1933 and seek unspecified damages and other relief. We believe that the claims are without merit and intend to defend the lawsuits vigorously. From time to time, we may become subject to other legal proceedings, claims or litigation arising in the ordinary course of business. In addition, we may receive letters alleging infringement of patents or other intellectual property rights. We do not believe that any liability from any reasonably foreseeable disposition of these legal actions and claims, individually or in the aggregate, would have a material effect on our business, operating results, cash flows or financial condition. The lawsuits described above are still in their early stages and the final outcome, including our liability, if any, with respect to the claims in the lawsuits, are uncertain. If an unfavorable outcome were to occur in the litigation, the impact could be material to our business, financial condition, cash flow or results of operations, depending on the specific circumstances of the outcome. We cannot make a reasonable estimate of the potential loss or range of loss, if any, arising from these matters. We accrue for loss contingencies when it is both probable that we will incur the loss and when we can reasonably estimate the amount of the loss or range of loss. If we determine that a loss is reasonably possible and can reasonably estimate the range of the loss, then we disclose the range of the loss. Leases and Contractual Obligations We lease office space under noncancelable operating leases in San Francisco, California. On May 21, 2015, we entered into a new office space lease in San Francisco, California, in order to expand our office facilities. The lease extends to June 30, 2021, with a five year renewal option. The total rent obligation under the lease is $12.8 million . There were no other material changes in our contractual obligations from those disclosed in our Annual Report on Form 10-K for the year ended December 31, 2014. Please see Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations - Liquidity and Capital Resources” in our Annual Report on Form 10-K for a description of our contractual obligations.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	6 Months Ended
	Jun. 30, 2015
Equity and Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity (Deficit)	Stockholders’ Equity Common Stock As of June 30, 2015 , we had 54,678,735 shares of Class A common stock and 39,574,120 shares of Class B common stock outstanding. Stock Options Activity A summary of stock option activity for the six months ended June 30, 2015 is as follows (in thousands, except share and per share amounts): Options Outstanding Weighted- Average Exercise Price Aggregate Intrinsic Value Balance at December 31, 2014 16,392,539 $ 4.40 $ 128,541 Stock option grants 491,900 $ 8.95 Stock options exercised (3,107,786 ) $ 1.02 Stock options canceled (1,766,650 ) $ 6.80 Balance at June 30, 2015 12,010,003 $ 5.11 $ 53,906 The total grant-date fair value of stock options granted during the six months ended June 30, 2015 and 2014 was $2.3 million and $28.4 million , respectively. The fair value of each option grant was estimated on the date of grant using the Black-Scholes option-valuation model with the following assumptions and fair value per share: Six Months Ended June 30, 2015 2014 Volatility 53% 60% Expected life (in years) 6.17 5.0-6.2 Risk-free interest rate 1.38%-1.91% 1.53%-1.99% Dividend yield —% —% As of June 30, 2015 , we had $27.7 million in unrecognized compensation cost related to non-vested stock options, which is expected to be recognized over a weighted-average period of approximately 2.8 years. Restricted Stock Units A summary of restricted stock unit activity for the six months ended June 30, 2015 is as follows : Number of Weighted- Balance at December 31, 2014 1,398,893 $ 11.06 Restricted Stock Units granted 3,318,000 $ 8.73 Restricted Stock Units vested — $ — Restricted Stock Units forfeited (316,900 ) $ 10.26 Balance at June 30, 2015 4,399,993 $ 9.36 As of June 30, 2015 , there was a total of $38.3 million in unrecognized compensation cost related to restricted stock units, which is expected to be recognized over a weighted-average period of approximately 3.6 years. In June 2015, we awarded performance stock units (PSUs) to certain employees. The number of shares that will eventually vest depends on achievement of performance targets for 2015, as determined by the compensation committee of our board of directors, and may range from 0 percent to 150 percent of the targeted award amount. The PSUs will vest over the period of two years in quarterly installments subject to recipients' continued service through the vesting date of November 15, 2017 in order to earn the shares. The compensation expense associated with the PSUs is expensed using the accelerated method.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rate for the three and six months ended June 30, 2015 and 2014 was zero percent, primarily as a result of the estimated tax loss for the year and the change in valuation allowance. There were no material changes to unrecognized tax benefits in the three and six months ended June 30, 2015 , and we do not anticipate that unrecognized tax benefits will significantly increase or decrease in the next 12 months. At June 30, 2015 , all unrecognized tax benefits are subject to a full valuation allowance and, if recognized, will not affect the effective tax rate.

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period . Diluted net loss per share is computed by giving effect to all potential shares of common stock, including Preferred Stock and outstanding stock options and warrants, to the extent dilutive. Basic and diluted net loss per share was the same for each period presented as the inclusion of all potential shares of common stock outstanding would have been anti-dilutive. Net loss is allocated based on the contractual participation rights of the Class A and Class B common stock as if the earnings for the year have been distributed. As the liquidation and dividend rights are identical, the net loss is allocated on a proportionate basis. The following table presents the calculation of basic and diluted net loss per share for our common stock (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Class A Class B Class A Class B Class A Class B Class A Class B Net loss $ (13,086 ) $ (8,126 ) $ (18,671 ) $ (3,105 ) $ (25,658 ) $ (15,197 ) $ (43,850 ) $ (2,207 ) Weighted-average shares used to compute basic and diluted net loss per share 57,870 35,934 76,755 12,765 58,282 34,519 50,731 2,553 Basic and diluted net loss per share $ (0.23 ) $ (0.23 ) $ (0.24 ) $ (0.24 ) $ (0.44 ) $ (0.44 ) $ (0.86 ) $ (0.86 ) The following securities were excluded from the calculation of diluted net loss per share for common stock because their effect would have been anti-dilutive for the periods presented (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Stock options and restricted common stock 16,410 17,908 16,410 17,908 Warrants 115 115 115 115 Total 16,525 18,023 16,525 18,023

Summary of Significant Accoun18

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Basis of Accounting Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (GAAP), for interim financial information and with the instructions to Form 10-Q and Article 10 of Securities and Exchange Commission (SEC), Regulation S-X. In the opinion of management, the information herein reflects all adjustments, consisting only of normal recurring adjustments except as otherwise noted, considered necessary for a fair statement of results of operations, financial position and cash flows. The condensed consolidated financial statements include the results of Castlight and its wholly owned U.S. subsidiary. The results for the interim periods presented are not necessarily indicative of the results expected for any future period. The condensed consolidated balance sheet as of December 31, 2014 included herein was derived from the audited financial statements as of that date. The following information should be read in conjunction with the audited financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2014 . There have been no changes to our significant accounting policies described in our Annual Report on Form 10-K that have had a material impact on our condensed consolidated financial statements and related notes.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires us to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements, as well as the reported amounts of revenue and expenses during the reporting period. These estimates include, but are not limited to, the determination of the relative selling prices for our services, certain assumptions used in the valuation of our equity awards, and the capitalization and estimated useful life of internal-use software development costs. Actual results could differ from those estimates, and such differences could be material to our consolidated financial position and results of operations.
Recently Issued and Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements In April 2015, the Financial Accounting Standards Board (FASB) issued new accounting guidance Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. This guidance is intended to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement, primarily to determine whether the arrangement includes a sale or license of software. The guidance will be effective for us beginning January 1, 2016 . Early adoption is permitted. We have elected not to early adopt. The adoption of this guidance is not expected to have a material impact on our condensed consolidated financial statements. In May 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09 regarding ASC Topic 606, Revenue from Contracts with Customers. The standard provides principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance will be effective for us beginning January 1, 2018. Early adoption is not permitted. We are evaluating the accounting, transition and disclosure requirements of the standard and cannot currently estimate the financial statement impact of adoption.

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	At June 30, 2015 and December 31, 2014 , respectively, marketable securities consisted of the following (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value June 30, 2015 U.S. agency obligations $ 145,414 $ 16 $ (5 ) $ 145,425 Money market mutual funds 8,015 — — 8,015 153,429 16 (5 ) 153,440 Included in cash and cash equivalents 20,535 — — 20,535 Included in marketable securities $ 132,894 $ 16 $ (5 ) $ 132,905 Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2014 U.S. agency obligations $ 177,297 $ 4 $ (44 ) $ 177,257 U.S. treasury securities 5,580 1 — 5,581 Money market mutual funds 1,919 — — 1,919 184,796 5 (44 ) 184,757 Included in cash and cash equivalents 3,480 — — 3,480 Included in marketable securities $ 175,093 $ 5 $ (41 ) $ 175,057 Included in marketable securities, noncurrent $ 6,223 $ — $ (3 ) $ 6,220

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The following tables present information about our assets that are measured at fair value on a recurring basis using the above input categories (in thousands): Level 1 Level 2 Total June 30, 2015 Cash equivalents: Money market mutual funds 8,015 — 8,015 U.S. agency obligations — 12,520 12,520 Marketable securities: U.S. agency obligations — 132,905 132,905 $ 8,015 $ 145,425 $ 153,440 Level 1 Level 2 Total December 31, 2014 Cash equivalents: Money market mutual funds $ 1,919 $ — $ 1,919 U.S. agency obligations — 1,561 1,561 Marketable securities: U.S. agency obligations — 175,696 175,696 U.S. treasury securities — 5,581 5,581 $ 1,919 $ 182,838 $ 184,757

Property and equipment, net (Ta

Property and equipment, net (Tables)	6 Months Ended
	Jun. 30, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property and equipment consisted of the following (in thousands): As of June 30, 2015 December 31, 2014 Leasehold improvements $ 1,058 $ 1,058 Computer equipment 3,641 3,247 Software 874 874 Capitalization of internal-use software 1,155 291 Furniture and equipment 301 301 Construction in process 537 — Total 7,566 5,771 Accumulated depreciation (3,051 ) (2,141 ) Property and equipment, net $ 4,515 $ 3,630

Deferred Revenue (Tables)

Deferred Revenue (Tables)	6 Months Ended
	Jun. 30, 2015
Deferred Revenue Disclosure [Abstract]
Deferred Revenue, by Arrangement, Disclosure	Deferred revenue consisted of the following (in thousands): As of June 30, 2015 December 31, 2014 Subscription $ 17,373 $ 14,826 Professional services—implementation 3,622 2,974 Professional services—communications 3,130 2,908 Total current 24,125 20,708 Subscription 2,090 1,950 Professional services—implementation 4,816 4,327 Professional services—communications 732 375 Total noncurrent 7,638 6,652 Total $ 31,763 $ 27,360

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	6 Months Ended
	Jun. 30, 2015
Equity and Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Other Share-based Compensation, Activity [Table Text Block]	A summary of restricted stock unit activity for the six months ended June 30, 2015 is as follows : Number of Weighted- Balance at December 31, 2014 1,398,893 $ 11.06 Restricted Stock Units granted 3,318,000 $ 8.73 Restricted Stock Units vested — $ — Restricted Stock Units forfeited (316,900 ) $ 10.26 Balance at June 30, 2015 4,399,993 $ 9.36
Schedule of Share-based Compensation, Stock Options, Activity	A summary of stock option activity for the six months ended June 30, 2015 is as follows (in thousands, except share and per share amounts): Options Outstanding Weighted- Average Exercise Price Aggregate Intrinsic Value Balance at December 31, 2014 16,392,539 $ 4.40 $ 128,541 Stock option grants 491,900 $ 8.95 Stock options exercised (3,107,786 ) $ 1.02 Stock options canceled (1,766,650 ) $ 6.80 Balance at June 30, 2015 12,010,003 $ 5.11 $ 53,906
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The fair value of each option grant was estimated on the date of grant using the Black-Scholes option-valuation model with the following assumptions and fair value per share: Six Months Ended June 30, 2015 2014 Volatility 53% 60% Expected life (in years) 6.17 5.0-6.2 Risk-free interest rate 1.38%-1.91% 1.53%-1.99% Dividend yield —% —%

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table presents the calculation of basic and diluted net loss per share for our common stock (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Class A Class B Class A Class B Class A Class B Class A Class B Net loss $ (13,086 ) $ (8,126 ) $ (18,671 ) $ (3,105 ) $ (25,658 ) $ (15,197 ) $ (43,850 ) $ (2,207 ) Weighted-average shares used to compute basic and diluted net loss per share 57,870 35,934 76,755 12,765 58,282 34,519 50,731 2,553 Basic and diluted net loss per share $ (0.23 ) $ (0.23 ) $ (0.24 ) $ (0.24 ) $ (0.44 ) $ (0.44 ) $ (0.86 ) $ (0.86 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following securities were excluded from the calculation of diluted net loss per share for common stock because their effect would have been anti-dilutive for the periods presented (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Stock options and restricted common stock 16,410 17,908 16,410 17,908 Warrants 115 115 115 115 Total 16,525 18,023 16,525 18,023

Marketable Securities (Details)

Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 153,429	$ 184,796
Unrealized Gains	16	5
Unrealized Losses	(5)	(44)
Fair Value	153,440	184,757
Included in cash and cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,535	3,480
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	20,535	3,480
Included in marketable securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	132,894	175,093
Unrealized Gains	16	5
Unrealized Losses	(5)	(41)
Fair Value	132,905	175,057
Included in marketable securities, noncurrent [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		6,223
Unrealized Gains		0
Unrealized Losses		(3)
Fair Value		6,220
U.S. agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	145,414	177,297
Unrealized Gains	16	4
Unrealized Losses	(5)	(44)
Fair Value	145,425	177,257
U.S. treasury securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		5,580
Unrealized Gains		1
Unrealized Losses		0
Fair Value		5,581
Money market mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,015	1,919
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	$ 8,015	$ 1,919

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Jun. 30, 2015 - USD ($)	Total	Total
Fair Value Disclosures [Abstract]
Available-for-sale Securities, Gross Realized Gain (Loss)	$ 0	$ 0
Available-for-sale Securities, Maturity Period		1 year

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Marketable securities:
Marketable securities	$ 153,440	$ 184,757
Money market mutual funds [Member]
Marketable securities:
Marketable securities	8,015	1,919
U.S. agency obligations [Member]
Marketable securities:
Marketable securities	145,425	177,257
U.S. treasury securities [Member]
Marketable securities:
Marketable securities		5,581
Fair Value, Measurements, Recurring
Marketable securities:
Assets, Fair Value Disclosure	153,440	184,757
Fair Value, Measurements, Recurring | Money market mutual funds [Member]
Cash equivalents:
Cash equivalents	8,015	1,919
Fair Value, Measurements, Recurring | U.S. agency obligations [Member]
Cash equivalents:
Cash equivalents	12,520	1,561
Marketable securities:
Marketable securities	132,905	175,696
Fair Value, Measurements, Recurring | U.S. treasury securities [Member]
Marketable securities:
Marketable securities		5,581
Fair Value, Measurements, Recurring | Level 1 [Member]
Marketable securities:
Assets, Fair Value Disclosure	8,015	1,919
Fair Value, Measurements, Recurring | Level 1 [Member] | Money market mutual funds [Member]
Cash equivalents:
Cash equivalents		1,919
Fair Value, Measurements, Recurring | Level 1 [Member] | U.S. agency obligations [Member]
Cash equivalents:
Cash equivalents	0	0
Marketable securities:
Marketable securities	0	0
Fair Value, Measurements, Recurring | Level 1 [Member] | U.S. treasury securities [Member]
Marketable securities:
Marketable securities		0
Fair Value, Measurements, Recurring | Level 2 [Member]
Marketable securities:
Assets, Fair Value Disclosure	145,425	182,838
Fair Value, Measurements, Recurring | Level 2 [Member] | Money market mutual funds [Member]
Cash equivalents:
Cash equivalents	0	0
Fair Value, Measurements, Recurring | Level 2 [Member] | U.S. agency obligations [Member]
Cash equivalents:
Cash equivalents	12,520	1,561
Marketable securities:
Marketable securities	$ 132,905	175,696
Fair Value, Measurements, Recurring | Level 2 [Member] | U.S. treasury securities [Member]
Marketable securities:
Marketable securities		$ 5,581

Property and equipment, net (De

Property and equipment, net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Property, Plant and Equipment [Abstract]
Depreciation Expense	$ 0.5	$ 0.3	$ 0.9	$ 0.6

Property and equipment, net - S

Property and equipment, net - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and Equipment	$ 7,566	$ 5,771
Capitalization of internal-use software	1,155	291
Accumulated depreciation	(3,051)	(2,141)
Property and equipment, net	4,515	3,630
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment	1,058	1,058
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment	3,641	3,247
Software [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment	874	874
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment	301	301
Asset under Construction [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment	$ 537	$ 0

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014
Related Party Transaction [Line Items]
Payments to acquire interest in related party		$ 3,125	$ 0
Lyra Health [Member]
Related Party Transaction [Line Items]
Payments to acquire interest in related party	$ 3,100

Deferred Revenue - Components o

Deferred Revenue - Components of Deferred Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Deferred Revenue Arrangement [Line Items]
Total current	$ 24,125	$ 20,708
Total noncurrent	7,638	6,652
Total	31,763	27,360
Subscription [Member]
Deferred Revenue Arrangement [Line Items]
Total current	17,373	14,826
Total noncurrent	2,090	1,950
Professional Services - Implementation [Member]
Deferred Revenue Arrangement [Line Items]
Total current	3,622	2,974
Total noncurrent	4,816	4,327
Professional Services - Communications [Member]
Deferred Revenue Arrangement [Line Items]
Total current	3,130	2,908
Total noncurrent	$ 732	$ 375

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies (Details) - Jun. 30, 2015 - USD ($) $ in Millions	Total
Commitments and Contingencies Disclosure [Abstract]
Operating leases, renewal term	5 years
Future minimum payments due	$ 12.8

Stockholders' Equity (Deficit33

Stockholders' Equity (Deficit) - Summary of Stock by Class (Details)	Jun. 30, 2015shares
Class A [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued	54,678,735
Class B [Member]
Class of Stock [Line Items]
Common Stock, Shares, Issued	39,574,120

Stockholders' Equity (Deficit34

Stockholders' Equity (Deficit) - Summary of Stock Option Activity (Details) - 6 months ended Jun. 30, 2015 - USD ($) $ / shares in Units, $ in Thousands	Total
Options Outstanding
Beginning Balance	16,392,539,000
Stock option grants	491,900,000
Stock options exercised	(3,107,786,000)
Stock options canceled	(1,766,650,000)
Ending Balance	12,010,003,000
Weighted- Average Exercise Price
Beginning Balance	$ 5.11
Stock option grants	8.95
Stock options exercised	1.02
Stock options canceled	6.80
Ending Balance	$ 4.40
Aggregate Intrinsic Value
Beginning Balance	$ 128,541
Ending Balance	$ 53,906

Stockholders' Equity (Deficit35

Stockholders' Equity (Deficit) - Stock Options Activity and Stock-based Compensation (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Equity and Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Granted, Value, Share-based Compensation, Gross	$ 2.3	$ 28.4
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	$ 27.7
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 9 months 18 days

Stockholders' Equity (Deficit36

Stockholders' Equity (Deficit) - Assumptions Related to Share-based Compensation (Details) - Stock Option [Member]	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	53.00%	60.00%
Risk-free interest rate, minimum	1.38%	1.53%
Risk-free interest rate, maximum	1.91%	1.99%
Dividend yield	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility	53.00%	60.00%
Expected life (in years)	6 years 2 months 1 day	5 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility
Expected life (in years)		6 years 2 months

Stockholders' Equity (Deficit37

Stockholders' Equity (Deficit) - Summary of Restricted Stock Unit Activity (Details) - Jun. 30, 2015 - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Total	Total
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 9 months 18 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance at December 31, 2014		1,398,893
Restricted Stock Units granted (1)	3,318,000
Restricted Stock Units vested	0
Restricted Stock Units forfeited	(316,900)
Balance at June 30, 2015	4,399,993	4,399,993
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Balance at December 31, 2014		$ 11.06
Restricted Stock Units granted (1)	$ 8.73
Restricted Stock Units vested	0
Restricted Stock Units forfeited	10.26
Balance at June 30, 2015	$ 9.36	$ 9.36
Unrecognized compensation cost	$ 38.3	$ 38.3
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		3 years 7 months 17 days

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	0.00%	0.00%	0.00%	0.00%

Net Loss per Share - Calculatio

Net Loss per Share - Calculation of Basic and Diluted EPS for Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Table] [Line Items]
Net loss	$ (21,212)	$ (21,776)	$ (40,855)	$ (46,057)
Weighted-average shares used to compute basic and diluted net loss per Class A and B share	93,804	89,520	92,801	53,284
Basic and diluted net loss per share (in usd per share)	$ (0.23)	$ (0.24)	$ 0	$ 0
Class A [Member]
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Table] [Line Items]
Net loss	$ (13,086)	$ (18,671)	$ (25,658)	$ (43,850)
Weighted-average shares used to compute basic and diluted net loss per Class A and B share	57,870	76,755	58,282	50,731
Basic and diluted net loss per share (in usd per share)	$ (0.23)	$ (0.24)	$ (0.44)	$ (0.86)
Class B [Member]
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Table] [Line Items]
Net loss	$ (8,126)	$ (3,105)	$ (15,197)	$ (2,207)
Weighted-average shares used to compute basic and diluted net loss per Class A and B share	35,934	12,765	34,519	2,553
Basic and diluted net loss per share (in usd per share)	$ (0.23)	$ (0.24)	$ (0.44)	$ (0.86)

Net Loss per Share - Summary of

Net Loss per Share - Summary of Antidilutive Securities (Details) - Class A [Member] - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	16,525	18,023	16,525	18,023
Stock Options and Restricted Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	16,410	17,908	16,410	17,908
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	115	115	115	115