Athenahealth (ATHN) 10-K 4 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 01, 2016	Jun. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	ATHN
Entity Registrant Name	Athenahealth Inc
Entity Central Index Key	1,131,096
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		38,957,284
Entity Public Float			$ 4,284,454,879

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 141,927	$ 73,787
Marketable securities	0	40,950
Accounts receivable, net	148,157	121,710
Prepaid expenses and other current assets	30,176	22,177
Total current assets	320,260	258,624
Property and equipment, net	321,524	271,552
Capitalized software costs, net	107,517	56,574
Purchased intangible assets, net	126,239	139,422
Goodwill	229,157	198,049
Investments and other assets	13,965	6,399
Total assets	1,118,662	930,620
Current liabilities:
Accounts payable	10,768	9,410
Accrued compensation	88,122	71,768
Accrued expenses	51,452	37,033
Line of credit	0	35,000
Long-term debt	10,762	14,550
Deferred revenue	32,593	28,949
Deferred tax liability, net	0	8,449
Total current liabilities	193,697	205,159
Deferred rent, net of current portion	31,118	19,412
Long-term debt, net of current portion	287,353	157,822
Deferred revenue, net of current portion	55,946	54,473
Long-term deferred tax liability, net	1,254	10,417
Other long-term liabilities	5,988	8,214
Total liabilities	$ 575,356	$ 455,497
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value: 5,000 shares authorized; no shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	$ 0	$ 0
Common stock, $0.01 par value: 125,000 shares authorized; 40,209 shares issued and 38,931 shares outstanding at December 31, 2015; 39,402 shares issued and 38,124 shares outstanding at December 31, 2014	403	395
Additional paid-in capital	522,443	443,259
Treasury stock, at cost, 1,278 shares	(1,200)	(1,200)
Accumulated other comprehensive (loss) income	(848)	24,188
Retained earnings	22,508	8,481
Total stockholders’ equity	543,306	475,123
Total liabilities and stockholders’ equity	$ 1,118,662	$ 930,620

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, par value (dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	5,000,000	5,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value (dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	125,000,000	125,000,000
Common stock, shares issued (shares)	40,209,000	39,402,000
Common stock, shares outstanding (shares)	38,931,000	38,124,000
Treasury stock, shares (shares)	1,278,000	1,278,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Business services	$ 247,919	$ 224,990	$ 215,403	$ 197,763	$ 201,072	$ 179,711	$ 175,949	$ 154,502	$ 886,075	$ 711,234	$ 563,237
Implementation and other	9,613	11,078	9,291	8,671	12,142	10,717	9,973	8,533	38,653	41,365	31,766
Total revenue	257,532	236,068	224,694	206,434	213,214	190,428	185,922	163,035	924,728	752,599	595,003
Expense:
Direct operating	97,253	94,850	89,899	84,557	76,274	79,343	74,774	72,148	366,559	302,539	238,672
Selling and marketing	66,196	55,927	54,413	53,365	50,533	45,206	50,722	43,227	229,901	189,688	149,488
Research and development	23,579	22,560	24,387	23,728	19,802	18,087	16,417	15,155	94,254	69,461	57,639
General and administrative	37,484	34,778	36,103	36,212	33,592	31,800	30,443	29,357	144,577	125,192	99,776
Depreciation and amortization	26,277	24,763	22,101	20,352	18,071	17,258	15,186	14,249	93,493	64,764	43,575
Total expense	250,789	232,878	226,903	218,214	198,272	191,694	187,542	174,136	928,784	751,644	589,150
Operating (loss) income	6,743	3,190	(2,209)	(11,780)	14,942	(1,266)	(1,620)	(11,101)	(4,056)	955	5,853
Other income (expense):
Interest expense	(1,604)	(1,620)	(1,513)	(1,059)	(911)	(1,244)	(1,275)	(1,265)	(5,796)	(4,695)	(3,905)
Other income (expense)	23	7,590	21,081	44	27	26	(6)	(171)	28,738	(124)	283
Total other income (expense)	(1,581)	5,970	19,568	(1,015)	(884)	(1,218)	(1,281)	(1,436)	22,942	(4,819)	(3,622)
Income (loss) before income tax (provision) benefit	5,162	9,160	17,359	(12,795)	14,058	(2,484)	(2,901)	(12,537)	18,886	(3,864)	2,231
Income tax (provision) benefit	2,553	(3,365)	(8,010)	3,963	(5,329)	853	739	4,482	(4,859)	745	363
Net income (loss)	$ 7,715	$ 5,795	$ 9,349	$ (8,832)	$ 8,729	$ (1,631)	$ (2,162)	$ (8,055)	$ 14,027	$ (3,119)	$ 2,594
Net (loss) income per share - Basic (in dollars per share)	$ 0.20	$ 0.15	$ 0.24	$ (0.23)	$ 0.23	$ (0.04)	$ (0.06)	$ (0.21)	$ 0.36	$ (0.08)	$ 0.07
Net (loss) income per share - Diluted (in dollars per share)	$ 0.19	$ 0.15	$ 0.24	$ (0.23)	$ 0.22	$ (0.04)	$ (0.06)	$ (0.21)	$ 0.35	$ (0.08)	$ 0.07
Weighted average shares used in computing net income (loss) per share:
Basic (in shares)	38,873	38,714	38,574	38,278	38,097	37,999	37,860	37,484	38,611	37,862	36,856
Diluted (in shares)	39,809	39,536	39,340	38,278	39,040	37,999	37,860	37,484	39,625	37,862	38,257

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 14,027	$ (3,119)	$ 2,594
Other comprehensive (loss) income
Unrealized (loss) gain on securities, net of tax of $3,485, $15,005, and $5 for the years ended December 31, 2015, 2014, and 2013, respectively	(7,709)	24,845	13
Reclassification adjustments for gains on sales of marketable securities included in net income, net of tax of $11,520 for the year ended December 31, 2015	(17,136)	0	0
Unrealized gain (loss) on change in fair value of interest rate swap, net of tax of $13, $9, and $101 for the years ended December 31, 2015, 2014, and 2013, respectively	21	101	(253)
Foreign currency translation adjustment	(212)	(312)	(125)
Total other comprehensive (loss) income	(25,036)	24,634	(365)
Comprehensive (loss) income	$ (11,009)	$ 21,515	$ 2,229

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on securities, tax expense (benefit)	$ (3,485)	$ 15,005	$ 5
Reclassification adjustment for gain on securities, tax	11,520
Unrealized gain (loss) on interest rate derivative, tax	$ 13	$ 9	$ 101

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive (Loss) Income	Retained Earnings	Total Stockholders' Equity
Beginning Balance, in shares at Dec. 31, 2012		37,572		(1,278)
Beginning Balance at Dec. 31, 2012		$ 376	$ 303,547	$ (1,200)	$ (81)	$ 9,006	$ 311,648
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			44,842				44,842
Stock options exercised and restricted stock units vested, shares		983
Stock options exercised and restricted stock units vested, net		$ 11	15,805				15,816
Common stock issued under employee stock purchase plan, shares		45
Common stock issued under employee stock purchase plan			3,500				3,500
Tax benefit realized from stock-based awards	$ 6,900		6,051				6,051
Fair value of vested stock options and restricted stock units assumed			13,028				13,028
Net settlement of acquired company’s board of directors equity shares			(5,806)				(5,806)
Net income (loss)	2,594					2,594	2,594
Other comprehensive loss	(365)				(365)		(365)
Ending Balance, in shares at Dec. 31, 2013		38,600		(1,278)
Ending Balance at Dec. 31, 2013		$ 387	380,967	$ (1,200)	(446)	11,600	391,308
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			60,258				60,258
Stock options exercised and restricted stock units vested, shares		758
Stock options exercised and restricted stock units vested, net		$ 8	(12,388)				(12,380)
Common stock issued under employee stock purchase plan, shares		44
Common stock issued under employee stock purchase plan			4,550				4,550
Tax benefit realized from stock-based awards	9,900		9,872				9,872
Net income (loss)	(3,119)					(3,119)	(3,119)
Other comprehensive loss	24,634				24,634		24,634
Ending Balance, in shares at Dec. 31, 2014		39,402		(1,278)
Ending Balance at Dec. 31, 2014	475,123	$ 395	443,259	$ (1,200)	24,188	8,481	475,123
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation			71,398				71,398
Stock options exercised and restricted stock units vested, shares		752
Stock options exercised and restricted stock units vested, net		$ 7	(5,008)				(5,001)
Common stock issued under employee stock purchase plan, shares		55
Common stock issued under employee stock purchase plan		$ 1	5,602				5,603
Tax benefit realized from stock-based awards	10,300		7,192				7,192
Net income (loss)	14,027					14,027	14,027
Other comprehensive loss	(25,036)				(25,036)		(25,036)
Ending Balance, in shares at Dec. 31, 2015		40,209		(1,278)
Ending Balance at Dec. 31, 2015	$ 543,306	$ 403	$ 522,443	$ (1,200)	$ (848)	$ 22,508	$ 543,306

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 14,027	$ (3,119)	$ 2,594
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	118,022	93,806	61,853
Excess tax benefit from stock-based awards	(12,925)	(10,060)	(6,910)
Deferred income tax	(8,542)	(11,670)	(7,044)
Stock-based compensation expense	64,134	55,558	42,648
Gain on sale of marketable securities	(28,656)	0	0
Other reconciling adjustments	129	(224)	9
Changes in operating assets and liabilities:
Accounts receivable, net	(25,318)	(34,367)	(3,399)
Prepaid expenses and other current assets	4,236	4,285	3,283
Other long-term assets	(2,722)	596	(66)
Accounts payable	2,763	2,546	(233)
Accrued expenses and other long-term liabilities	8,226	10,083	(21)
Accrued compensation	17,223	26,339	5,775
Deferred revenue	3,181	3,248	(3,090)
Deferred rent	10,066	12,084	(2,091)
Net cash provided by operating activities	163,844	149,105	93,308
CASH FLOWS FROM INVESTING ACTIVITIES:
Capitalized software costs	(97,761)	(53,477)	(29,123)
Purchases of property and equipment	(87,214)	(76,092)	(38,260)
Proceeds from sales and maturities of investments	29,756	0	56,245
Payments on acquisitions, net of cash acquired	(39,890)	0	(410,161)
Change in restricted cash	0	3,000	(1,643)
Other investing activities	(3,960)	(750)	(2,000)
Net cash used in investing activities	(199,069)	(127,319)	(424,942)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock under stock plans and warrants	22,088	21,041	31,133
Taxes paid related to net share settlement of stock awards	(21,486)	(28,879)	(12,075)
Excess tax benefit from stock-based awards	12,925	10,060	6,910
Proceeds from long-term debt	300,000	0	200,000
Proceeds from line of credit	60,000	0	155,000
Payments on line of credit	(95,000)	0	(120,000)
Payments on long-term debt	(173,750)	(15,000)	(11,250)
Net settlement of acquired company’s board of directors equity shares	0	0	(5,806)
Debt issuance costs	(987)	0	(1,699)
Payment of contingent consideration accrued at acquisition date	0	0	(525)
Net cash provided by (used in) financing activities	103,790	(12,778)	241,688
Effects of exchange rate changes on cash and cash equivalents	(425)	(223)	(40)
Net increase (decrease) in cash and cash equivalents	68,140	8,785	(89,986)
Cash and cash equivalents at beginning of period	73,787	65,002	154,988
Cash and cash equivalents at end of period	141,927	73,787	65,002
Non-cash transactions
Property, equipment, and purchased software recorded in accounts payable and accrued expenses	12,503	12,036	1,667
Non-cash leasehold improvements	2,317	5,933	0
Fair value of equity awards assumed	0	0	13,028
Additional disclosures
Cash paid for interest, net	5,744	4,499	2,877
Cash paid (refunded) for taxes	$ 619	$ (1,931)	$ 1,348

NATURE OF OPERATIONS AND SUMMAR

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES General – athenahealth, Inc. (the “Company,” “we,” “us,” or “our”) provides cloud-based business services that help health care providers achieve and sustain financial health by collecting more revenue and greatly reducing their administrative work burden. We deliver the majority of our service offerings using a single instance of cloud-based software, which we refer to as athenaNet, which we continuously update to improve our services. Our customers consist of medical group practices ranging in size throughout the United States of America. In March 2013, we acquired Epocrates, Inc. (“Epocrates”). Epocrates is recognized for developing a leading medical application among U.S. physicians for clinical content, practice tools, and health industry engagement at the point of care. The features available through the Epocrates services are used by health care providers to make more informed prescribing decisions, improve workflow, and enhance patient safety. In January 2015, we acquired Razor Insights, LLC (“RazorInsights”), a provider of cloud-based billing and EHR software services to rural and community hospitals. Principles of Consolidation – The accompanying consolidated financial statements include the results of operations of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates – The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions are used for, but are not limited to: (1) revenue recognition, including the expected customer life; (2) asset impairments; (3) depreciable lives of assets; (4) fair value of stock-based compensation; (5) allocation of direct and indirect cost of sales; (6) fair value of identifiable purchased tangible and intangible assets in a business combination; (7) determination of the reporting unit(s) for goodwill impairment testing; (8) litigation reserves; and (9) capitalized software costs. Actual results could significantly differ from those estimates. Segment Reporting – Operating segments are identified as components of an enterprise about which separate discrete financial information is evaluated by the chief operating decision maker (“CODM”) or decision-making group in assessing performance and making decisions regarding resource allocation. We use consolidated financial information in determining how to allocate resources and assess performance, and have determined that we operate in one segment. The CODM, our Chief Executive Officer, uses non-GAAP adjusted operating income (defined as the sum of GAAP net income (loss) before (provision for) benefit from income taxes, total other income (expense), stock-based compensation expense, amortization of capitalized stock-based compensation related to software development, amortization of purchased intangible assets, integration and transaction costs, and restructuring costs) as the measure of our profit on a regular basis. As of December 31, 2015 and 2014 , our CODM determined that, as our acquired businesses are fully integrated, he reviews and assesses the business as one operating segment. Revenue Recognition – We recognize revenue when there is evidence of an arrangement, the service has been provided to the customer, the collection of the fees is reasonably assured, and the amount of fees to be paid by the customer is fixed or determinable. We derive revenue from two sources: business services, and implementation and other services. Business services includes revenue from our medical billing and revenue cycle management service; electronic health records (“EHR”) service; patient engagement service; order transmission service; patient access and care coordination service; population health management service; subscriptions, sponsored clinical information, and decision support services for our point of care clinical application; and consulting, training, and go-live support. Our clients typically purchase one -year service contracts for our integrated services that renew automatically. In most cases, our clients may terminate their agreements with 90 days notice without cause. We typically retain the right to terminate client agreements in a similar timeframe. Our clients are billed monthly, in arrears, based either upon a percentage of collections posted to athenaNet; minimum fees; flat fees; or per-claim fees, where applicable. We do not recognize revenue for athenahealth-branded business services fees until these collections are made, as the services fees are not fixed and determinable until such time. Unbilled amounts that have been earned are accrued and recorded as revenue or deferred revenue, as appropriate, and are included in our accounts receivable balances. Members enter into subscriptions to the Epocrates point of care medical application via an internal or third-party digital distribution platform or through a redeemable license code which expires within six to 12 months of issuance. Basic subscriptions are free and do not expire. Premium subscription fees are assessed on the length of the subscription period, typically one year. Payment occurs at the time of order, which is in advance of the services being performed, and such amounts are recorded as deferred revenue. Premium subscriptions are recognized ratably over the contracted term of delivery, typically one year. If a license code expires before it is redeemed, revenue is recognized upon expiration. Sponsored clinical information and decision support service clients typically enter into arrangements that contain various combinations of services that are generally fulfilled within one year. The clients are charged a fee for the entire group of services to be provided and are typically billed a portion of the contracted fee upon signing of the agreement with the balance billed upon one or more future milestones. Because billings typically occur in advance of services being performed, these amounts are recorded as deferred revenue when billed. Each service deliverable within these multiple element revenue arrangements is accounted for as a separate unit if the delivered item or items have value to the customer on a stand-alone basis. This is the only criteria we need to assess because our revenue arrangements do not include a general right of return, as we deliver services and not products. We consider a deliverable to have stand-alone value if we sell this item separately, if the item is sold by another vendor, or could be resold by the customer. Each service deliverable within these multiple element arrangements is then accounted for as a separate unit; deliverables not meeting the criteria for being a separate unit of accounting are combined with a deliverable that does meet that criterion, and we allocate arrangement consideration to each deliverable using our best estimate of selling price (“BESP”) if we do not have vendor specific objective evidence (“VSOE”) of fair value or third-party evidence (“TPE”) of fair value. Any discount or premium inherent in the arrangement is allocated to each element in the arrangement based on the relative fair value of each element. Multiple element arrangements require judgments as to how to allocate the arrangement consideration to each deliverable. Due to the specific nature of these agreements and the variability in the amount of discount offered for individual services across multiple contracts, we have not been able to conclude that a consistent number of stand-alone sales of a deliverable have been priced within a reasonably narrow range in order to assert that we have established VSOE. Due to the fact that our services differ significantly from that of our peers and contain a significant level of customization, the comparable pricing of products with similar functionality cannot be obtained and we are also typically unable to determine TPE. We therefore use BESP to establish fair value and allocate total consideration to each element in the arrangement. The objective of BESP is to determine the price at which we would transact a sale if the service were sold on a stand-alone basis. We determine BESP for a service by considering multiple factors including an analysis of recent stand-alone sales of that service, market conditions, competitive landscape, internal costs, gross margin objectives, and pricing practices. Implementation and other services revenue consists primarily of the amortization of deferred revenue on implementation services. Historically, all of these fees were billed upfront and recorded as deferred revenue until the implementation was complete, and then, as the service did not have stand-alone value, it was recognized ratably over the longer of the life of the agreement or the expected customer life, which is currently estimated to be 12 years. We evaluate the length of the amortization period of the implementation fees based on our experience with customer contract renewals and consideration of the period over which those customers will receive benefits from our current portfolio of services. During 2014, we began to sell go-live and training support services separate from the required implementation services. Go-live and training support services can be purchased by the customer from us or third-party vendors, and therefore, have stand-alone value and are recognized upon delivery of service. When we made this change, we began to include the fees associated with the required implementation services in our ongoing monthly rate; therefore, they are being recognized ratably over the customer life. Previously deferred revenue balances related to implementation services that were billed upfront and did not have stand-alone value will continue to be amortized over those remaining customer lives. Certain expenses related to the implementation go-live and training of a customer, such as out-of-pocket travel, are typically reimbursed by the customer. This is accounted for as both revenue and expense in the period the cost is incurred. Other revenue consists primarily of tenant revenue which is straight-lined over the term of the lease. Direct Operating Expense – Direct operating expense consists primarily of compensation expense (including stock-based compensation) related to personnel who provide services, including implementation of clients, costs associated with our business partner outsourcing arrangements and clearing house, and claim processing costs. We expense implementation costs as incurred. We include in direct operating expense all service costs incurred to fulfill our customer contracts. Direct operating expense also includes costs associated with third-party tenant and other non-core revenue. Direct operating expense does not include allocated amounts for rent, occupancy costs, depreciation, or amortization, except for amortization related to certain purchased intangible assets. Research and Development Expense – Research and development expense consists primarily of compensation expense (including stock-based compensation) for research and development employees and consulting fees for third-party developers. All such costs are expensed as incurred, except for certain internal use software costs, which may be capitalized (refer to Note 6 – Capitalized Software Costs). Research and development expense does not include allocated amounts for rent, occupancy costs, depreciation, or amortization. Stock-Based Compensation – We account for share-based awards, including shares issued under employee stock purchase plans, stock options, and restricted stock units with compensation cost measured using the fair value of the awards issued. We use the Black-Scholes option pricing model to value share-based awards and determine the related compensation expense. The assumptions used in calculating the fair value of share-based awards represent management’s best estimates. We generally issue previously unissued shares for the exercise of stock options; however, we may reissue previously acquired treasury shares to satisfy these awards in the future. Certain employees have received awards for which the ultimate number of shares that will be subject to vesting is dependent upon the achievement of certain financial targets for the year. Such determination is not made until the award’s vesting determination date, which is the date our fiscal year financial statements are available. The award is initially recorded at the maximum attainable number of shares that is most likely to be subject to vesting based on available financial forecasts as of the date of grant. This amount is adjusted on a quarterly basis as new financial forecasts become available. Stock‑based compensation expense for these awards is recorded over the requisite service period, generally four years. Such awards generally vest ratably over four years from the vesting determination date. Advertising Expenses – Advertising expenses are expensed as incurred and are included in selling and marketing expense in the Consolidated Statements of Income. Advertising expense totaled $28.1 million , $15.5 million and $14.2 million for the years ended December 31, 2015, 2014, and 2013, respectively. Cash and Cash Equivalents – We consider all highly liquid investments with an original or remaining maturity from the Company’s date of purchase of 90 days or less to be cash equivalents. Investments – Management determines the appropriate classification of investments at the time of purchase based upon management’s intent with regard to such investments. Our convertible notes receivable from privately-held companies are accounted for as available-for-sale investments which are carried at cost, which we believe approximates fair value. Upon conversion, if any, we assess whether such equity investments should be accounted for on a cost basis or equity method, depending on whether we believe we have significant influence over the investee. Marketable securities, if any, are also accounted for as available-for-sale investments and recorded at fair value. Unrealized holding gains and losses on available-for-sale investments are included in accumulated other comprehensive (loss) income. The Company determines realized gains and losses based on the specific identification method. Management monitors and assesses individual investments for other-than-temporary impairment on a quarterly basis. We had no available-for-sale equity securities as of December 31, 2015 due to the sale of our holdings in Castlight Health, Inc. stock during the three months ended June 30, 2015 and September 30, 2015. We had the following available-for-sale equity securities as of December 31, 2014 : Cost Gross Unrealized Gain Fair Value Marketable equity securities $ 1,100 $ 39,850 $ 40,950 Concentrations of Credit Risk – Financial instruments that potentially subject us to concentrations of credit risk are cash equivalents, investments, derivatives, notes receivables, and accounts receivable. We attempt to limit our credit risk associated with cash equivalents and investments by investing and/or depositing in highly-rated corporate and financial institutions, and engaging with highly-rated financial institutions as counterparties to our derivative transactions. With respect to customer accounts receivable, we manage our credit risk by performing ongoing credit evaluations of our customers. No single customer accounted for a significant amount of revenues for the years ended December 31, 2015, 2014, and 2013 . No single customer accounted for a significant portion of accounts receivable as of December 31, 2015 and 2014 . Accounts Receivable – Accounts receivable represents unbilled amounts and amounts due from customers for business services. Accounts receivable are stated net of an allowance for uncollectible accounts, which is determined by establishing reserves for specific accounts and consideration of historical and estimated probable losses. Activity in the allowance for doubtful accounts is as follows: Years Ended December 31, 2015 2014 2013 Beginning balance $ 557 $ 1,691 $ 1,771 Provision 692 (769 ) 791 Write-offs (529 ) (365 ) (871 ) Ending balance $ 720 $ 557 $ 1,691 Prepaid Expenses and Other Current Assets – Prepaid expenses and other current assets consist of the following: Years Ended December 31, 2015 2014 2013 Prepaid expenses $ 17,882 $ 11,578 $ 10,006 Other receivables 12,294 10,599 6,715 Prepaid expenses and other current assets $ 30,176 $ 22,177 $ 16,721 Property and Equipment – Property and equipment are stated at cost less accumulated depreciation. Depreciation is calculated on a straight-line basis over the following estimated useful lives: Equipment, furniture, and fixtures 3-5 years Aircraft 20 years Buildings 30-40 years Building improvements 10-25 years Land improvements 10 years Leasehold improvements are depreciated using the straight-line method over the lesser of the useful life of the improvements or the applicable lease terms, excluding renewal periods. Costs associated with maintenance and repairs are expensed as incurred. Capitalized Interest Cost – Interest costs related to major capital projects, specifically our corporate headquarters campus project and capitalized internal-use software costs, are capitalized until each underlying asset is placed into service. Capitalized interest is calculated by multiplying the effective interest rate of the outstanding debt by the qualifying costs. As the qualifying asset is placed into service, the qualifying asset and the related capitalized interest are amortized over the useful life of the related asset. Capitalized Software Costs – We capitalize certain costs related to the development of athenaNet services and other internal-use software. Costs incurred during the application development phase are capitalized only when we believe it is probable the development will result in new or additional functionality. The types of costs capitalized during the application development phase include employee wages and stock-based compensation expense, as well as external contractor costs for individuals working on these projects. Costs related to the preliminary project stage and post-implementation activities are expensed as incurred. Internal-use software is amortized on a straight-line basis over its estimated useful life. The estimated useful life of the software is two to five years (refer to Note 6 – Capitalized Software Costs). Long-Lived Assets – Long-lived assets to be held and used are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Determination of recoverability of long-lived assets is based on an estimate of undiscounted future cash flows resulting from the use of the asset and its eventual disposition, as compared with the asset carrying value. Measurement of an impairment loss for long-lived assets that management expects to hold and use is based on the fair value of the asset. Long-lived assets to be disposed of are reported at the lower of carrying amount or fair value, less costs to sell. No impairment losses have been recognized in the years ended December 31, 2015, 2014, and 2013 . Goodwill – Goodwill is recorded as the difference, if any, between the aggregate consideration paid for an acquisition and the fair value of the identifiable net tangible and intangible assets acquired. Goodwill is not amortized but is evaluated for impairment annually or more frequently if indicators of impairment are present or changes in circumstances suggest that impairment may exist. We evaluate the carrying value of our goodwill annually on November 30. The first step of the goodwill impairment test compares the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of our reporting unit exceeds its carrying amount, the goodwill of the reporting unit is not considered impaired. If the carrying amount of our reporting unit exceeds its fair value, the second step of the goodwill impairment test is performed to measure the amount of impairment loss, if any. The second step of the goodwill impairment test compares the implied fair value of the affected reporting unit’s goodwill with the carrying value of that goodwill. No impairment losses have been recognized in the years ended December 31, 2015, 2014, and 2013 . Purchased Intangible Assets – Purchased intangible assets consist of technology, a physician network, content, a trade name and trademark, customer backlog, non-compete agreements, customer relationships, above market leases, leases in place, and an indefinite-lived license related to the development of our headquarters' campus, most of which were acquired in connection with business acquisitions, and are amortized over their estimated useful lives based on the pattern of economic benefit expected from each asset. We concluded for certain purchased intangible assets that the pattern of economic benefit approximated the straight-line method, and therefore, the use of the straight-line method was appropriate, as the majority of the cash flows will be recognized ratably over the estimated useful lives and there is no degradation of the cash flows over time. Accrued expenses and accrued compensation – Accrued expenses consist of the following: As of December 31, 2015 2014 Accrued bonus $ 59,006 $ 38,938 Accrued vacation 9,826 8,106 Accrued payroll 9,386 19,846 Accrued commissions 9,904 4,878 Accrued compensation expenses $ 88,122 $ 71,768 Other accrued liabilities $ 42,636 $ 31,162 Accrued property and equipment additions 8,816 5,871 Accrued expenses $ 51,452 $ 37,033 Deferred Rent – Deferred rent consists of rent escalation, tenant improvement allowances and other incentives received from landlords related to the operating leases for our facilities. Rent escalation represents the difference between actual operating lease payments due and straight-line rent expense, which we record over the term of the lease. The excess is recorded as a deferred credit in the early periods of the lease, when cash payments are generally lower than straight-line rent expense, and is reduced in the later periods of the lease when payments begin to exceed the straight-line expense. Tenant allowances from landlords for tenant improvements are generally comprised of cash received from the landlord or paid on our behalf as part of the negotiated terms of the lease. These tenant improvement allowances and other incentives are recorded when realizable as deferred rent and are amortized as a reduction of periodic rent expense, over the term of the applicable lease. Deferred Revenue – Deferred revenue primarily consists of billings or payments received in advance of the revenue recognition criteria being met. Deferred revenue includes amounts associated with multiple element arrangements associated with sponsored clinical information and decision support services which are recognized based upon contractual deliverables, and previously, deferred implementation services fees which will continue to be recognized as revenue ratably over the longer of the life of the agreement or the expected customer life, which is currently estimated to be 12 years. Deferred revenue that will be recognized during the succeeding 12-month period is recorded as current deferred revenue and the remaining portion is recorded as non-current. Preferred Stock – Our Board of Directors has the authority, without further action by stockholders, to issue up to 5,000 shares of preferred stock in one or more series. Our Board of Directors may designate the rights, preferences, privileges, and restrictions of the preferred stock, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preference, and number of shares constituting any series or the designation of any series. The issuance of preferred stock could have the effect of restricting dividends on our common stock, diluting the voting power of our common stock, impairing the liquidation rights of our common stock, or delaying or preventing a change in control. The ability to issue preferred stock could delay or impede a change in control. As of December 31, 2015 and 2014 , no shares of preferred stock were outstanding. Common Stock – Common stockholders are entitled to one vote per share and dividends, when declared by the Board of Directors, subject to any preferential rights of preferred stockholders. Business Combinations – We apply business combination accounting when we acquire control over a business. Business combinations are accounted for at fair value. The associated acquisition costs are expensed as incurred and recorded in general and administrative expenses; non-controlling interests, if any, are reflected at fair value at the acquisition date; in-process research and development, if any, is recorded at fair value as an intangible asset at the acquisition date; restructuring costs associated with a business combination are expensed; contingent consideration is measured at fair value at the acquisition date, with changes in the fair value after the acquisition date affecting earnings; changes in deferred tax asset valuation allowances and income tax uncertainties after the measurement period affect income tax expense; and goodwill is determined as the excess of the fair value of the consideration conveyed in the acquisition over the fair value of the net assets acquired. The accounting for business combinations requires estimates and judgments as to expectations for future cash flows of the acquired business, and the allocation of those cash flows to identifiable intangible assets, in determining the estimated fair value for assets and liabilities acquired. The fair values assigned to tangible and intangible assets acquired and liabilities assumed, are based on management’s estimates and assumptions, including valuations that utilize customary valuation procedures and techniques. If the actual results differ from the estimates and judgments used in these estimates, the amounts recorded in the financial statements could result in a possible impairment of the intangible assets and goodwill, or require acceleration of the amortization expense of finite-lived intangible assets. The results of the acquired businesses’ operations are included in the Consolidated Statements of Income of the combined entity beginning on the date of acquisition. We have applied this acquisition method to the transaction described in Note 2 – Business Combinations. Related Party Transaction – We have a long-term investment in a vendor. The total expense related to this vendor for the years ended December 31, 2015, 2014, and 2013 was $23.6 million , $11.3 million , and $1.5 million , respectively, and the total amount payable related to this vendor at December 31, 2015 and 2014 was $2.3 million and $1.3 million , respectively. Income Taxes – Deferred tax assets and liabilities relate to temporary differences between the financial reporting and income tax bases of assets and liabilities and are measured using enacted tax rates and laws expected to be in effect at the time of their reversal. A valuation allowance is established to reduce net deferred tax assets if, based on the available positive and negative evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. In making such determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax planning strategies, and recent financial results. We recognize a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Our income tax positions must meet a more-likely-than-not recognition threshold at the balance sheet date to be recognized in the related period. Our policy is to record interest and penalties related to unrecognized tax benefits in income tax expense. Sales and Use Taxes – Our services are subject to sales and use taxes in certain jurisdictions. Our contractual agreements with customers provide that payment of any sales or use tax assessments is the responsibility of the customer. In certain jurisdictions, sales taxes are collected from the customer and remitted to the respective agencies. These taxes are recorded on a net basis and excluded from revenue and expense in our financial statements as presented. Incentives Received from Governmental Bodies – From time to time, we receive incentives from various government agencies and programs. We account for the portion of the credits that are expected to be used as grants by reducing general and administrative expense. Credits which are expected to be used to reduce general and administrative expense are recognized when the requirements to earn the credits have been met. We recognized $4.1 million and $1.2 million from our participation in incentive programs during the years ended December 31, 2015 and 2014, respectively. Foreign Currency Translation – The financial position and results of operations of our foreign subsidiary are measured using local currency as the functional currency. Assets and liabilities are translated at the rate of exchange in effect at the end of each reporting period. Revenues and expenses are translated at the average exchange rate for the period. Foreign currency translation gains and losses are recorded within other comprehensive (loss) income. Employee Benefit Plan – We sponsor a 401(k) retirement savings plan (the “401(k) Plan”), under which eligible employees may contribute, on a pre-tax basis, specified percentages of their compensation, subject to maximum aggregate annual contributions imposed by the Internal Revenue Code of 1986. All employee contributions are allocated to the employee’s individual account and are invested in various investment options as directed by the employee. Employees’ cash contributions are fully vested and non-forfeitable. We may make a discretionary contribution in any year, subject to authorization by our Board of Directors. During the years ended December 31, 2015, 2014, and 2013 , our contributions to the 401(k) Plan were $5.3 million , $4.5 million , and $3.2 million , respectively. New Accounting Pronouncements – In November 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2015-17, Balance Sheet Classification of Deferred Taxes , which will require entities to present all deferred tax assets (“DTAs”) and deferred tax liabilities (“DTLs”) as non-current on the balance sheet. This guidance is effective for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. Early adoption is permitted, and entities may choose whether to adopt this update prospectively or retrospectively. We have evaluated ASU 2015-17 and determined that its adoption will not have a material effect on our financial position or earnings. On December 31, 2015, we elected to adopt ASU 2015-17 and change our method of classifying DTAs and DTLs as either current or non-current to classifying all DTAs and DTLs as non-current, and have chosen to apply a prospective method. Prior balance sheets were not retrospectively adjusted. In September 2015, the FASB issued ASU 2015-16, Simplifying the Accounting for Measurement-Period Adjustments , that eliminates the requirement to restate prior period financial statements for measurement period adjustments. The new guidance requires that the cumulative impact of a measurement period adjustment (including the impact on prior periods) be recognized in the reporting period in which the adjustment is identified. The new standard should be applied prospectively to measurement period adjustments that occur after the effective date. This guidance is effective for public companies for interim and annual periods beginning after December 15, 2015. Early adoption is permitted for all entities. We have evaluated ASU 2015-16 and determin

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS RazorInsights On January 13, 2015, we acquired RazorInsights for $39.9 million in cash after net working capital adjustments. We acquired RazorInsights for the assembled workforce, technology, customer base, and to accelerate our entry into the inpatient market. The fair value of net assets acquired, after measurement period adjustments totaling $1.0 million , was $8.9 million , including purchased intangible assets of $7.0 million related to technology acquired and $4.0 million related to customer relationships. The $31.1 million excess of purchase consideration over the fair value of net assets acquired is allocated to goodwill, which is deductible for U.S. income tax purposes. We incurred transaction costs in connection with the acquisition of $0.3 million , which are included in general and administrative expenses. The fair values assigned to assets acquired and liabilities assumed were based on information that was available as of the date of the acquisition and upon completion of the valuation.

NET INCOME (LOSS) PER SHARE

NET INCOME (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
NET INCOME (LOSS) PER SHARE	NET INCOME (LOSS) PER SHARE Basic net income (loss) per share is computed by dividing net income (loss) by the weighted average number of common shares outstanding during the period. Diluted net income (loss) per share is computed by dividing net income (loss) by the weighted average number of common shares outstanding and potentially dilutive securities outstanding during the period under the treasury stock method. Potentially dilutive securities include stock options, restricted stock units, and shares to be purchased under the employee stock purchase plan. Under the treasury stock method, dilutive securities are assumed to be exercised at the beginning of the periods and as if funds obtained thereby were used to purchase common stock at the average market price during the period. Securities are excluded from the computations of diluted net income (loss) per share if their effect would be anti-dilutive to earnings per share; therefore, in periods of net loss, shares used to calculate basic and dilutive net loss per share are equivalent. The following table reconciles the weighted average shares outstanding for basic and diluted net income (loss) per share for the periods indicated: Years Ended December 31, 2015 2014 2013 Net income (loss) $ 14,027 $ (3,119 ) $ 2,594 Weighted average shares used in computing basic net income (loss) per share 38,611 37,862 36,856 Net income (loss) per share – Basic $ 0.36 $ (0.08 ) $ 0.07 Net income (loss) $ 14,027 $ (3,119 ) $ 2,594 Weighted average shares used in computing basic net income (loss) per share 38,611 37,862 36,856 Effect of dilutive securities 1,014 — 1,401 Weighted average shares used in computing diluted net income (loss) per share 39,625 37,862 38,257 Net income (loss) per share – Diluted $ 0.35 $ (0.08 ) $ 0.07 The computation of diluted net income per share does not include 0.7 million and 0.4 million of stock options and restricted stock units for the years ended December 31, 2015 and December 31, 2013 , respectively, because their inclusion would have an anti-dilutive effect on net income per share.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS As of December 31, 2015 and 2014 , the carrying amounts of cash and cash equivalents, receivables, accounts payable, and accrued expenses approximated their estimated fair values because of the short-term nature of these financial instruments. Derivatives are carried at fair value, as determined using standard valuation models, and adjusted when necessary for credit risk. Refer to Note 9 – Debt for additional information. As of December 31, 2015 , we had $300.0 million outstanding on our term loan facility and we had not drawn on our revolving credit facility under the 2015 Credit Agreement (see Note 9 – Debt). As of December 31, 2014 , we had $173.8 million outstanding on our term loan facility and $35.0 million outstanding on our revolving credit facility under the 2013 Credit Agreement. The credit facilities under both credit agreements carry a variable interest rate set at current market rates, and as such, the carrying values approximate fair values. Our More Disruption Please (“MDP”) Accelerator portfolio is a program designed to cultivate heath care information technology start-ups and expand services offered to our physician network. Portfolio investments as of December 31, 2015 and 2014 are in the form of convertible notes receivable and equity, and are recorded in Investments and other assets on our Consolidated Balance Sheets. At December 31, 2015 and 2014, as there is no indication of performance risk and while conversion is contemplated for certain investments, we currently estimate that the fair value of the notes receivable approximates cost, based on inputs including the original transaction prices, our own recent transactions in the same or similar instruments, completed or pending third-party transactions in the underlying investments, subsequent rounds of financing, and changes in financial ratios or cash flows (Level 3). Marketable equity securities and money market funds are valued using a market approach based upon the quoted market prices of identical instruments when available or other observable inputs such as trading prices of identical instruments in inactive markets or similar securities. Derivative financial instruments are used to manage certain of the Company’s interest rate exposures. We do not enter into derivatives for trading or speculative purposes. Our interest rate swap agreement was designed to manage exposure to interest rates on our variable rate indebtedness. We have designated the interest rate swap agreement as a cash flow hedge. Changes in the fair value of the interest rate swap are recognized, net of taxes, in other comprehensive income (loss) (“OCI”) until the hedged items are recognized in earnings. Hedge ineffectiveness associated with the interest rate swap, if any, will be reported in interest expense. For the years ended December 31, 2015 and 2014 , no amount was recognized in earnings for our interest rate swap. There was no ineffectiveness associated with the interest rate swap during the years ended December 31, 2015 and 2014 , nor was any amount excluded from ineffectiveness testing. We do not expect that any of the $0.2 million of pre-tax unrealized losses included in accumulated other comprehensive (loss) income at December 31, 2015 will be reclassified into earnings within the next 12 months. This amount will vary due to fluctuations in interest rates. We are exposed to credit loss in the event of non-performance by the swap counterparty. The estimated fair value of our interest rate swap agreement with a certain financial institution at December 31, 2015 and 2014 was a liability of $0.2 million and $0.2 million , respectively, based on inputs other than quoted prices that are observable for the interest rate swap (Level 2). Inputs include present value of fixed and projected floating rate cash flows over term of the swap contract. Refer to Note 9 – Debt for further information. The following table presents information about our financial assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2015 and December 31, 2014 , and indicates the fair value hierarchy of the valuation techniques we utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities, and fair values determined by Level 2 inputs utilize quoted prices (unadjusted) in inactive markets for identical assets or liabilities obtained from readily available pricing sources for similar instruments. The fair values determined by Level 3 inputs are unobservable values which are supported by little or no market activity. It is our policy to recognize transfers between levels of the fair value hierarchy, if any, at the end of the reporting period; however, there have been no such transfers during any of the periods presented. Fair Value Measurements as of December 31, 2015, Using Level 1 Level 2 Level 3 Total Cash and cash equivalents: Money market $ 10,006 $ — $ — $ 10,006 Debt Securities: MDP Accelerator portfolio $ — $ — $ 1,250 $ 1,250 Total assets $ 10,006 $ — $ 1,250 $ 11,256 Interest rate swap liability (a) $ — $ (210 ) $ — $ (210 ) Total liabilities $ — $ (210 ) $ — $ (210 ) Fair Value Measurements as of December 31, 2014, Using Level 1 Level 2 Level 3 Total Available-for-sale investments: Marketable equity securities $ 40,950 $ — $ — $ 40,950 Debt Securities: MDP Accelerator portfolio $ — $ — $ 750 $ 750 Total assets $ 40,950 $ — $ 750 $ 41,700 Interest rate swap liability (b) $ — $ (244 ) $ — $ (244 ) Total liabilities $ — $ (244 ) $ — $ (244 ) (a) Recorded in other short-term liabilities on the Consolidated Balance Sheets. (b) Recorded in other long-term liabilities on the Consolidated Balance Sheets. The following table presents our financial instruments measured at fair value using unobservable inputs (Level 3) as of the years ended December 31, 2015 and 2014 : Fair Value Measurements Using Unobservable Inputs (Level 3) Year Ended December 31, 2015 Year Ended December 31, 2014 Balance, beginning of period $ 750 $ — Conversion (250 ) — Additions 750 750 Balance, end of period $ 1,250 $ 750

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT We had no capital leases for the years ended December 31, 2015 and December 31, 2014 . Property and equipment consists of the following: Years Ended December 31, 2015 2014 Equipment $ 113,221 $ 93,583 Furniture and fixtures 25,152 14,760 Leasehold improvements 32,534 18,113 Aircraft 15,054 15,054 Building 131,746 131,746 Building improvements 81,163 49,671 Land 23,059 23,059 Land improvements 5,893 4,339 Total property and equipment, at cost 427,822 350,325 Accumulated depreciation (115,965 ) (96,416 ) Construction in progress 9,667 17,643 Property and equipment, net $ 321,524 $ 271,552 Depreciation expense on property and equipment was $40.1 million , $31.5 million , and $25.5 million for the years ended December 31, 2015, 2014, and 2013 , respectively.

CAPITALIZED SOFTWARE COSTS

CAPITALIZED SOFTWARE COSTS	12 Months Ended
	Dec. 31, 2015
Research and Development [Abstract]
CAPITALIZED SOFTWARE COSTS	CAPITALIZED SOFTWARE COSTS Capitalized software consisted of the following: Years ended December 31, 2015 2014 Capitalized internal-use software development costs $ 114,484 $ 72,666 Acquired third party software licenses for internal use 25,710 15,873 Total gross capitalized software for internal-use 140,194 88,539 Accumulated amortization (61,603 ) (34,972 ) Capitalized internal-use software in process 28,926 3,007 Total capitalized software costs $ 107,517 $ 56,574 On January 23, 2015, we signed an agreement to purchase a suite of internally-developed clinical applications and an EHR system from Beth Israel Deaconess Medical Center, Inc. (“BIDMC”) referred to as webOMR for $22.0 million in cash which is included in capitalized internal-use software in process. This asset is recorded in the capitalized software costs, net line on our Consolidated Balance Sheet. The agreement also provides for up to an additional $18.0 million in contingent payments upon achievement of certain milestones in the future. In connection with the purchase of the webOMR technology, the parties also entered into a two -year collaboration agreement under which BIDMC will provide ongoing consultation services with respect to the webOMR technology and provide one of its facilities as a testing site for a new inpatient service offering. We purchased webOMR to accelerate our entry into the inpatient market. Capitalized software amortization expense totaled $53.4 million , $33.2 million and $18.0 million for the years ended December 31, 2015, 2014 and 2013, respectively. Future amortization expense for all capitalized software placed in service as of December 31, 2015 is estimated to be $54.0 million , $22.5 million and $2.1 million for the years ending December 31, 2015, 2016, and 2017, respectively.

GOODWILL AND PURCHASED INTANGIB

GOODWILL AND PURCHASED INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND PURCHASED INTANGIBLE ASSETS	GOODWILL AND PURCHASED INTANGIBLE ASSETS Goodwill The following table summarizes the activity related to the carrying value of our goodwill during the years ended December 31, 2015 and 2014 : Gross balance as of January 1, 2014 $ 198,049 Gross balance as of December 31, 2014 $ 198,049 Goodwill recorded in connection with the acquisition of Razor Insights, LLC 31,108 Gross balance as of December 31, 2015 $ 229,157 Purchased Intangible Assets Definite-lived intangible assets acquired as of December 31, 2015 and 2014 are as follows: December 31, 2015 Gross Accumulated Amortization Net Developed technology $ 13,500 $ (9,575 ) $ 3,925 Customer relationships 25,434 (12,100 ) 13,334 Doctor network 104,000 (15,196 ) 88,804 Drug information content 10,000 (5,608 ) 4,392 Trade name 11,500 (3,224 ) 8,276 Trademark 100 (2 ) 98 Above market leases 2,967 (2,449 ) 518 Leases in place 15,557 (8,892 ) 6,665 Total $ 183,058 $ (57,046 ) $ 126,012 December 31, 2014 Gross Accumulated Amortization Net Developed technology $ 9,721 $ (6,294 ) $ 3,427 Customer relationships 21,434 (9,555 ) 11,879 Doctor network 104,000 (9,792 ) 94,208 Drug information content 10,000 (3,608 ) 6,392 Trade name 11,500 (2,074 ) 9,426 Non-compete agreement 1,178 (873 ) 305 Above market leases 3,016 (916 ) 2,100 Leases in place 19,695 (8,065 ) 11,630 Total $ 180,544 $ (41,177 ) $ 139,367 Amortization expense for the years ended December 31, 2015, 2014, and 2013 was $24.0 million , $28.6 million , and $17.9 million , respectively, and is included in direct operating expenses. Estimated amortization expense, based upon our intangible assets at December 31, 2015 , is as follows: Year ending December 31, Amount 2016 20,290 2017 15,872 2018 14,597 2019 13,993 2020 12,650 Thereafter 48,610 Total $ 126,012 During the year ended December 31, 2015 , we purchased an indefinite-lived license of $0.2 million related to the development of our headquarters' campus.

OPERATING LEASES AND OTHER COMM

OPERATING LEASES AND OTHER COMMITMENTS	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
OPERATING LEASES AND OTHER COMMITMENTS	OPERATING LEASES AND OTHER COMMITMENTS We maintain operating leases for facilities and certain office equipment. The facility leases contain renewal options and require payments of certain utilities, taxes, and shared operating costs of each leased facility. The rental agreements expire at various dates from 2016 to 2030. During the year ended December 31, 2014, we expanded in four of our locations which are under operating lease. Rent expense totaled $9.8 million , $9.9 million , and $5.5 million for the years ended December 31, 2015, 2014, and 2013 , respectively. Future minimum lease payments under non-cancelable operating leases as of December 31, 2015 are as follows: Year ending December 31, Future Rent Payments 2016 $ 13,524 2017 14,060 2018 13,881 2019 13,388 2020 12,462 Thereafter 86,333 Total minimum lease payments $ 153,648

DEBT

DEBT	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
DEBT	DEBT On May 10, 2013, we entered into a $325.0 million senior credit facility consisting of a $200.0 million unsecured term loan facility and a $125.0 million unsecured revolving credit facility (the “Senior Credit Facility”). As of December 31, 2014, $173.8 million was outstanding on the unsecured term loan facility and $35.0 million was outstanding on the unsecured revolving credit facility. On May 5, 2015, we entered into an amended and restated credit agreement (the “2015 Credit Agreement”). The 2015 Credit Agreement amended and restated our previous credit agreement (the “2013 Credit Agreement”), and provides for a $500.0 million senior credit facility consisting of a $300.0 million unsecured term loan facility and a $200.0 million unsecured revolving credit facility (the “2015 Senior Credit Facility”). As of December 31, 2015, $300.0 million was outstanding on the unsecured term loan facility. A portion of the proceeds received from the 2015 Senior Credit Facility were used to repay the outstanding revolving loans under the 2013 Credit Agreement such that there were no revolving loans outstanding on the closing of the 2015 Credit Agreement. The 2015 Credit Agreement contains terms and conditions that are customary to credit facilities of this nature; it may be used to refinance existing indebtedness, and for working capital and other general corporate purposes. We may increase the revolving credit facility up to an additional $100.0 million and may increase the term loan facility to the extent that such amount will not cause us to be in breach of our financial covenants, subject to certain conditions, including obtaining lender commitments. The 2015 Senior Credit Facility matures on May 5, 2020, although we may prepay the 2015 Senior Credit Facility in whole or in part at any time without premium or penalty, and the unutilized portion of the commitments may be irrevocably reduced or terminated by us in whole or in part without penalty or premium. At our option, any loans under the 2015 Senior Credit Facility (other than swing line loans) will bear interest at a rate equal to (i) the British Bankers Association London Interbank Offered Rate (“LIBOR”) plus an interest margin based on our consolidated leverage ratio, or (ii) the base rate (which is the highest of (a) the Bank of America prime rate, (b) the Federal Funds rate plus 0.50% , and (c) one month LIBOR plus 1.00% ) plus an interest margin based on our consolidated leverage ratio. The interest rate for the 2015 Senior Credit Facility as of December 31, 2015 was 1.74% . We will pay a commitment fee during the term of the 2015 Senior Credit Facility, which varies between 0.20% and 0.40% based on our consolidated leverage ratio. We incurred financing fees of $1.0 million for the 2015 Senior Credit Facility, which are being amortized as interest expense in the Consolidated Statements of Income over the 5 -year term of the agreement. Future principal payments of the unsecured term loan facility at December 31, 2015 were as follows: Amount 2016 $ 11,250 2017 15,000 2018 20,625 2019 28,125 2020 225,000 Total $ 300,000 Less current portion 11,250 Long-term portion $ 288,750 During the quarter ended September 30, 2013, we entered into an interest rate swap agreement designed to fix the variable interest rate payable on $120.0 million of our variable rate debt at 0.8396% exclusive of the credit spread under the Senior Credit Facility. The fair value of the interest rate swap recognized in other short-term liabilities and in OCI was as follows: Fair Value Effective Date Notional Amount Fixed Rate Maturity December 31, 2015 December 31, 2014 August 31, 2013 120,000 0.8396 % August 31, 2016 $ (210 ) $ (244 ) Refer to Note 4 – Fair Value of Financial Instruments for further information.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION Total stock-based compensation expense for the years ended December 31, 2015, 2014, and 2013 was as follows: Year Ended December 31, 2015 2014 2013 Stock-based compensation charged to: Direct operating $ 14,558 $ 12,009 $ 7,778 Selling and marketing 18,457 14,581 12,057 Research and development 8,956 7,221 4,238 General and administrative 22,163 21,747 18,575 Total stock-based compensation expense $ 64,134 $ 55,558 $ 42,648 In addition, for the years ended December 31, 2015 and 2014 , $7.3 million and $4.7 million of stock-based compensation was capitalized in the line item "Capitalized software costs, net" in the Consolidated Balance Sheets. $4.4 million and $2.3 million of capitalized software costs was included in the line item "Depreciation and amortization" in the Consolidated Statements of Income. In 2007, the Board of Directors and our stockholders approved our 2007 Stock Option and Incentive Plan. The 2007 Stock Option and Incentive Plan was amended and restated in 2011 to: (i) remove an evergreen provision; (ii) increase the number of shares reserved for issuance by 1.3 million shares; (iii) set a multiplier for full value awards of 1.3 shares of stock for each share of stock subject to that award; (iv) set minimum restriction periods for stock awards; (v) set maximum awards payable for performance-based awards; (vi) add performance criteria; and (vii) make other administrative changes; and in 2012 to: (i) increase the number of shares reserved for issuance by 1.85 million shares; (ii) set a multiplier for full value awards of 1.66 shares of stock for each share of stock subject to that award; (iii) set a new minimum period for a performance cycle for cash-based awards; (iv) add performance criteria; (v) revise the share counting provision so that shares underlying awards other than stock options and stock appreciation rights may be withheld to satisfy tax withholding obligations; and (vi) extend its term through April 23, 2022 (as amended and restated, the “2007 Plan”); and in 2013 to: (i) increase the number of shares reserved for issuance by 1.66 million shares. Stock Options Options granted under the 2007 Plan may be incentive stock options or non-qualified stock options under the applicable provisions of the Internal Revenue Code. Incentive stock options are granted with exercise prices at or above the fair value of our common stock at the grant date as determined by the Board of Directors. Incentive stock options granted to employees who own more than 10% of the voting power of all classes of stock are granted with exercise prices at 110% of the fair value of our common stock at the date of the grant. Non-qualified stock options may be granted with exercise prices up to the fair value of our common stock on the date of the grant, as determined by the Board of Directors. All options granted vest over a range of one to four years and have contractual terms of between five and ten years. Options granted typically vest 25% per year over a total of four years at each anniversary. The following table presents the stock option activity for the year ended December 31, 2015 : Shares Weighted- Weighted- Aggregate Outstanding – January 1, 2015 1,850 $ 65.14 Granted 278 129.25 Exercised (436 ) 37.79 Forfeited (134 ) 126.88 Outstanding – as of December 31, 2015 1,558 78.94 5.8 $ 132,465 Exercisable – as of December 31, 2015 1,075 $ 57.50 4.9 $ 112,311 Vested and expected to vest as of December 31, 2015 1,482 $ 76.04 5.7 $ 129,955 Weighted-average fair value of options granted for the year ended December 31, 2015 $ 49.29 We recorded compensation expense in relation to these stock options of $11.6 million , $11.7 million , and $14.0 million , for the years ended December 31, 2015, 2014, and 2013 , respectively. The following table illustrates the range of assumptions used to compute stock-based compensation expense for awards granted: Year Ended December 31, 2015 2014 2013 Risk-free interest rate 1.06% - 1.57% .66% - 1.67% .35% - .75% Expected dividend yield —% —% —% Expected option term (years) 3.0 - 5.0 3.0 - 5.0 3.0 - 5.0 Expected stock volatility 40% - 42% 46% - 47% 41% - 45% The risk-free interest rate estimate was based on the U.S. Treasury rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected terms of the awards being valued. The expected dividend yield was based on our expectation of not paying dividends in the foreseeable future. We use company-specific historical and implied volatility information to generate the volatility assumptions. As of December 31, 2015 and 2014 , there was $11.4 million and $16.5 million , respectively, of unrecognized stock-based compensation expense related to unvested stock option share-based compensation arrangements granted under our stock award plans. This expense is expected to be recognized over a weighted-average period of approximately 2.1 years. The weighted average fair value of stock options granted during the years ended December 31, 2015 , 2014 , and 2013 was $49.29 , $77.55 , and $38.09 , respectively. The intrinsic value of options exercised during the years ended December 31, 2015 , 2014 , and 2013 was $44.3 million , $53.5 million , and $53.2 million , respectively. The intrinsic value is calculated as the difference between the market value of the stock on the date of purchase and the exercise price of the options. Restricted Stock Units The 2007 Plan also allows for granting of restricted stock unit awards under the terms of the plan. The majority of the restricted stock units vest in four equal, annual installments on the anniversaries of the vesting start date or in four equal, quarterly installments on anniversaries of the vesting date. We estimated the fair value of the restricted stock units using the market price of our common stock on the date of the grant. The fair value of restricted stock units is amortized on a straight-line basis over the vesting period. The following table presents the restricted stock unit activity for the year ended December 31, 2015 : Shares Weighted- Outstanding – January 1, 2015 1,210 $ 124.65 Granted 576 132.31 Vested (483 ) 103.31 Forfeited (150 ) 101.56 Outstanding – as of December 31, 2015 1,153 $ 136.06 As of December 31, 2015 , $93.5 million of total unrecognized compensation costs related to restricted stock units is expected to be recognized over a weighted average period of 2.7 years. Stock-based compensation expense of $51 million , $42.2 million , and $27.4 million was recorded for restricted stock units during the years ended December 31, 2015, 2014, and 2013 , respectively. The weighted average fair value of restricted stock units granted during the years ended December 31, 2015 , 2014 , and 2013 was $132.31 , $181.81 , and $98.34 , respectively. The intrinsic value of vested restricted stock units during the years ended December 31, 2015 , 2014 , and 2013 was $61.6 million , $78.5 million , and $35.2 million , respectively. Employee Stock Purchase Plan Our 2007 Employee Stock Purchase Plan allows employees of athenahealth and its subsidiaries as designated by our Board of Directors to purchase shares of our common stock. The purchase price is equal to 85% of the lower of the closing price of our common stock on (1) the first day of the purchase period or (2) the last day of the purchase period. The expense for the years ended December 31, 2015, 2014, and 2013 was $1.5 million , $1.7 million , and $1.2 million , respectively.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The components of income (loss) before income tax (provision) benefit for the years ended December 31, 2015, 2014, and 2013 were as follows: 2015 2014 2013 U.S. $ 17,130 $ (4,579 ) $ 1,536 Non-U.S. 1,756 715 695 Total $ 18,886 $ (3,864 ) $ 2,231 The components of our income tax (provision) benefit for the years ended December 31, 2015, 2014, and 2013 were as follows: 2015 2014 2013 Current Provision: Federal $ (11,810 ) $ (9,656 ) $ (4,225 ) State (764 ) (884 ) (1,495 ) Foreign (827 ) (385 ) (961 ) (13,401 ) (10,925 ) (6,681 ) Deferred Benefit: Federal 5,787 10,695 5,291 State 2,565 906 1,753 Foreign 190 69 — 8,542 11,670 7,044 Total income tax (provision) benefit $ (4,859 ) $ 745 $ 363 The components of our deferred income taxes as of December 31, 2015 and 2014 were as follows: 2015 2014 Deferred tax assets: State net operating loss carryforward $ 1,898 $ 1,694 Research and development tax credits 3,644 3,328 Allowances for accounts receivable 362 1,168 Deferred rent obligation 12,073 7,555 Stock compensation 29,306 25,264 Other accrued liabilities 2,860 2,223 Deferred revenue 20,107 17,797 Other 1,557 1,473 Total gross deferred tax assets 71,807 60,502 Valuation allowance (4,041 ) (3,420 ) Total deferred tax assets 67,766 57,082 Deferred tax liabilities: Intangible assets (34,599 ) (40,463 ) Capitalized software (23,624 ) (15,769 ) Property and equipment (10,502 ) (4,621 ) Investments 80 (14,913 ) Total deferred tax liabilities (68,645 ) (75,766 ) Net deferred tax liabilities $ (879 ) $ (18,684 ) During the years ended December 31, 2015 , 2014, and 2013, we utilized tax attributes to reduce the current tax provision by $12.9 million , $9.9 million , and $7.0 million , respectively. As of December 31, 2015 , we had federal and state net operating loss (“NOL”) carryforwards of approximately $85.6 million (which was comprised entirely of NOL carryforwards from stock-based compensation) and $67.9 million (which included $29.2 million of NOL carryforwards from stock-based compensation), respectively, to offset future federal and state taxable income. The federal NOL carryforwards expire at various times from 2020 through 2035 , and the state NOL carryforwards begin to expire in 2018 . As of December 31, 2014 , we had federal and state NOL carryforwards of approximately $73.6 million (which was comprised entirely of NOL carryforwards from stock-based compensation) and $67.7 million (which included $32.7 million of NOL carryforwards from stock-based compensation), respectively, to offset future federal and state taxable income. We generated NOL carryforwards from stock-based compensation deductions in excess of expenses recognized for financial reporting purposes (“excess tax benefits”). Excess tax benefits are realized when they reduce taxes payable, as determined using a “with and without” method, and are credited to additional paid-in capital rather than as a reduction of the income tax provision. During the years ended December 31, 2015, 2014, and 2013 , we realized excess tax benefits from federal and state tax deductions of $10.3 million , $9.9 million , and $6.9 million , respectively. As of December 31, 2015 , there are unrecognized federal and state excess tax benefits of $100.0 million and $33.4 million , respectively, which will be credited to additional paid-in capital when realized. Our research and development (“R&D”) tax credits carryforward is available to offset future federal and state taxes, and the credits expire at various times through 2035 . We have federal and state R&D credits of $14.3 million (which relates entirely to the utilization of credits under the without method of accounting related to stock-based compensation) and $6.7 million (which includes $4.1 million from the utilization of credits under the without method of accounting related to stock-based compensation), respectively. These benefits, when utilized to reduce taxes payable, will be credited to additional paid-in capital. A reconciliation of the federal statutory income tax rate to our effective income tax rate is as follows for the years ended December 31, 2015, 2014, and 2013 : 2015 2014 2013 Income tax computed at federal statutory tax rate 35 % 35 % 35 % State taxes, net of federal benefit 7 % 6 % (6 )% Research and development credits (32 )% 86 % (98 )% Permanent differences 13 % (87 )% 20 % Valuation allowance 3 % (21 )% 33 % Effective income tax rate 26 % 19 % (16 )% A reconciliation of the beginning and ending amount of uncertain tax benefits is as follows: 2015 2014 2013 Beginning uncertain tax benefits $ 5,813 $ 4,851 $ 1,761 Prior year – decreases — (79 ) (537 ) Prior year – increases 508 887 501 Acquired balances — — 2,339 Current year - decreases (454 ) (212 ) — Current year – increases 1,797 366 787 Ending uncertain tax benefits $ 7,664 $ 5,813 $ 4,851 Included in the balance of unrecognized tax benefits at December 31, 2015 are $6.7 million of tax benefits that, if recognized, would affect the effective tax rate. We anticipate that no material amounts of unrecognized tax benefits will either expire or be settled within 12 months of the reporting date. There were no interest and penalties included in the tax (provision) benefit for the year ended December 31, 2015. Interest and penalties included in the tax (provision) benefit amounted to $0.8 million for the year ended December 31, 2014. Accrued interest and penalties amounted to $1.2 million as of both December 31, 2015 and 2014 . The accrued interest and penalties balances were adjusted for foreign currency gains during the year ended December 31, 2014 of $0.3 million . We are subject to taxation in Federal, various states, and Indian jurisdictions. All carryforward attributes generated in prior years may still be adjusted upon examination by the Internal Revenue Service or other tax authorities if they have been used or will be used in a future period. As of December 31, 2015 , federal tax years after 2011, state tax years after 2010 and foreign tax years after 2007 remain open per the statute of limitations by the major taxing jurisdictions to which we are subject.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES We are engaged from time to time in certain legal disputes arising in the ordinary course of business, including employment discrimination claims and challenges to our intellectual property. We believe that we have adequate legal defenses and that the likelihood of a loss contingency relating to the ultimate disposition of any of these disputes is remote. When the likelihood of a loss contingency becomes at least reasonably possible with respect to any of these disputes, or, as applicable in the future, if there is at least a reasonable possibility that a loss exceeding amounts already recognized may have been incurred, we will revise our disclosures in accordance with the relevant authoritative guidance. Additionally, we will accrue a liability for loss contingencies when we believe that it is both probable that a liability has been incurred and that we can reasonably estimate the amount of the loss. We will review these accruals and adjust them to reflect ongoing negotiations, settlements, rulings, advice of legal counsel, and other relevant information. To the extent new information is obtained, and our views on the probable outcomes of claims, suits, assessments, investigations, or legal proceedings change, changes in our accrued liabilities would be recorded in the period in which such determination is made.

QUARTERLY FINANCIAL INFORMATION

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL INFORMATION (UNAUDITED)	QUARTERLY FINANCIAL INFORMATION (UNAUDITED) Selected quarterly financial information follows for the year ended December 31, 2015 : First Quarter Second Quarter Third Quarter Fourth Quarter Year Revenue: Business services $ 197,763 $ 215,403 $ 224,990 $ 247,919 $ 886,075 Implementation and other 8,671 9,291 11,078 9,613 38,653 Total revenue 206,434 224,694 236,068 257,532 924,728 Expense: Direct operating 84,557 89,899 94,850 97,253 366,559 Selling and marketing 53,365 54,413 55,927 66,196 229,901 Research and development 23,728 24,387 22,560 23,579 94,254 General and administrative 36,212 36,103 34,778 37,484 144,577 Depreciation and amortization 20,352 22,101 24,763 26,277 93,493 Total expense 218,214 226,903 232,878 250,789 928,784 Operating (loss) income (11,780 ) (2,209 ) 3,190 6,743 (4,056 ) Other (expense) income: Interest expense (1,059 ) (1,513 ) (1,620 ) (1,604 ) (5,796 ) Other income 44 21,081 7,590 23 28,738 Total other (expense) income (1,015 ) 19,568 5,970 (1,581 ) 22,942 (Loss) income before income tax benefit (provision) (12,795 ) 17,359 9,160 5,162 18,886 Income tax benefit (provision) 3,963 (8,010 ) (3,365 ) 2,553 (4,859 ) Net (loss) income $ (8,832 ) $ 9,349 $ 5,795 $ 7,715 $ 14,027 Net (loss) income per share – Basic $ (0.23 ) $ 0.24 $ 0.15 $ 0.20 $ 0.36 Net (loss) income per share – Diluted $ (0.23 ) $ 0.24 $ 0.15 $ 0.19 $ 0.35 Weighted average shares used in computing net (loss) income per share: Basic 38,278 38,574 38,714 38,873 38,611 Diluted 38,278 39,340 39,536 39,809 39,625 Selected quarterly financial information follows for the year ended December 31, 2014 : First Second Third Fourth Year Revenue: Business services $ 154,502 $ 175,949 $ 179,711 $ 201,072 $ 711,234 Implementation and other 8,533 9,973 10,717 12,142 41,365 Total revenue 163,035 185,922 190,428 213,214 752,599 Expense: Direct operating 72,148 74,774 79,343 76,274 302,539 Selling and marketing 43,227 50,722 45,206 50,533 189,688 Research and development 15,155 16,417 18,087 19,802 69,461 General and administrative 29,357 30,443 31,800 33,592 125,192 Depreciation and amortization 14,249 15,186 17,258 18,071 64,764 Total expense 174,136 187,542 191,694 198,272 751,644 Operating (loss) income (11,101 ) (1,620 ) (1,266 ) 14,942 955 Other (expense) income: Interest expense (1,265 ) (1,275 ) (1,244 ) (911 ) (4,695 ) Other income (171 ) (6 ) 26 27 (124 ) Total other (expense) income (1,436 ) (1,281 ) (1,218 ) (884 ) (4,819 ) (Loss) income before income tax benefit (provision) (12,537 ) (2,901 ) (2,484 ) 14,058 (3,864 ) Income tax benefit (provision) 4,482 739 853 (5,329 ) 745 Net (loss) income $ (8,055 ) $ (2,162 ) $ (1,631 ) $ 8,729 $ (3,119 ) Net (loss) income per share – Basic $ (0.21 ) $ (0.06 ) $ (0.04 ) $ 0.23 $ (0.08 ) Net (loss) income per share – Diluted $ (0.21 ) $ (0.06 ) $ (0.04 ) $ 0.22 $ (0.08 ) Weighted average shares used in computing net (loss) income per share: Basic 37,484 37,860 37,999 38,097 37,862 Diluted 37,484 37,860 37,999 39,040 37,862 Net income (loss) per share for the four quarters of each fiscal year may not sum to the total for the fiscal year due to the different number of shares outstanding during each period.

NATURE OF OPERATIONS AND SUMM22

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General – athenahealth, Inc. (the “Company,” “we,” “us,” or “our”) provides cloud-based business services that help health care providers achieve and sustain financial health by collecting more revenue and greatly reducing their administrative work burden. We deliver the majority of our service offerings using a single instance of cloud-based software, which we refer to as athenaNet, which we continuously update to improve our services. Our customers consist of medical group practices ranging in size throughout the United States of America. In March 2013, we acquired Epocrates, Inc. (“Epocrates”). Epocrates is recognized for developing a leading medical application among U.S. physicians for clinical content, practice tools, and health industry engagement at the point of care. The features available through the Epocrates services are used by health care providers to make more informed prescribing decisions, improve workflow, and enhance patient safety.
Principles of Consolidation	Principles of Consolidation – The accompanying consolidated financial statements include the results of operations of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates – The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions are used for, but are not limited to: (1) revenue recognition, including the expected customer life; (2) asset impairments; (3) depreciable lives of assets; (4) fair value of stock-based compensation; (5) allocation of direct and indirect cost of sales; (6) fair value of identifiable purchased tangible and intangible assets in a business combination; (7) determination of the reporting unit(s) for goodwill impairment testing; (8) litigation reserves; and (9) capitalized software costs. Actual results could significantly differ from those estimates.
Segment Reporting	Segment Reporting – Operating segments are identified as components of an enterprise about which separate discrete financial information is evaluated by the chief operating decision maker (“CODM”) or decision-making group in assessing performance and making decisions regarding resource allocation. We use consolidated financial information in determining how to allocate resources and assess performance, and have determined that we operate in one segment. The CODM, our Chief Executive Officer, uses non-GAAP adjusted operating income (defined as the sum of GAAP net income (loss) before (provision for) benefit from income taxes, total other income (expense), stock-based compensation expense, amortization of capitalized stock-based compensation related to software development, amortization of purchased intangible assets, integration and transaction costs, and restructuring costs) as the measure of our profit on a regular basis.
Revenue Recognition	Revenue Recognition – We recognize revenue when there is evidence of an arrangement, the service has been provided to the customer, the collection of the fees is reasonably assured, and the amount of fees to be paid by the customer is fixed or determinable. We derive revenue from two sources: business services, and implementation and other services. Business services includes revenue from our medical billing and revenue cycle management service; electronic health records (“EHR”) service; patient engagement service; order transmission service; patient access and care coordination service; population health management service; subscriptions, sponsored clinical information, and decision support services for our point of care clinical application; and consulting, training, and go-live support. Our clients typically purchase one -year service contracts for our integrated services that renew automatically. In most cases, our clients may terminate their agreements with 90 days notice without cause. We typically retain the right to terminate client agreements in a similar timeframe. Our clients are billed monthly, in arrears, based either upon a percentage of collections posted to athenaNet; minimum fees; flat fees; or per-claim fees, where applicable. We do not recognize revenue for athenahealth-branded business services fees until these collections are made, as the services fees are not fixed and determinable until such time. Unbilled amounts that have been earned are accrued and recorded as revenue or deferred revenue, as appropriate, and are included in our accounts receivable balances. Members enter into subscriptions to the Epocrates point of care medical application via an internal or third-party digital distribution platform or through a redeemable license code which expires within six to 12 months of issuance. Basic subscriptions are free and do not expire. Premium subscription fees are assessed on the length of the subscription period, typically one year. Payment occurs at the time of order, which is in advance of the services being performed, and such amounts are recorded as deferred revenue. Premium subscriptions are recognized ratably over the contracted term of delivery, typically one year. If a license code expires before it is redeemed, revenue is recognized upon expiration. Sponsored clinical information and decision support service clients typically enter into arrangements that contain various combinations of services that are generally fulfilled within one year. The clients are charged a fee for the entire group of services to be provided and are typically billed a portion of the contracted fee upon signing of the agreement with the balance billed upon one or more future milestones. Because billings typically occur in advance of services being performed, these amounts are recorded as deferred revenue when billed. Each service deliverable within these multiple element revenue arrangements is accounted for as a separate unit if the delivered item or items have value to the customer on a stand-alone basis. This is the only criteria we need to assess because our revenue arrangements do not include a general right of return, as we deliver services and not products. We consider a deliverable to have stand-alone value if we sell this item separately, if the item is sold by another vendor, or could be resold by the customer. Each service deliverable within these multiple element arrangements is then accounted for as a separate unit; deliverables not meeting the criteria for being a separate unit of accounting are combined with a deliverable that does meet that criterion, and we allocate arrangement consideration to each deliverable using our best estimate of selling price (“BESP”) if we do not have vendor specific objective evidence (“VSOE”) of fair value or third-party evidence (“TPE”) of fair value. Any discount or premium inherent in the arrangement is allocated to each element in the arrangement based on the relative fair value of each element. Multiple element arrangements require judgments as to how to allocate the arrangement consideration to each deliverable. Due to the specific nature of these agreements and the variability in the amount of discount offered for individual services across multiple contracts, we have not been able to conclude that a consistent number of stand-alone sales of a deliverable have been priced within a reasonably narrow range in order to assert that we have established VSOE. Due to the fact that our services differ significantly from that of our peers and contain a significant level of customization, the comparable pricing of products with similar functionality cannot be obtained and we are also typically unable to determine TPE. We therefore use BESP to establish fair value and allocate total consideration to each element in the arrangement. The objective of BESP is to determine the price at which we would transact a sale if the service were sold on a stand-alone basis. We determine BESP for a service by considering multiple factors including an analysis of recent stand-alone sales of that service, market conditions, competitive landscape, internal costs, gross margin objectives, and pricing practices. Implementation and other services revenue consists primarily of the amortization of deferred revenue on implementation services. Historically, all of these fees were billed upfront and recorded as deferred revenue until the implementation was complete, and then, as the service did not have stand-alone value, it was recognized ratably over the longer of the life of the agreement or the expected customer life, which is currently estimated to be 12 years. We evaluate the length of the amortization period of the implementation fees based on our experience with customer contract renewals and consideration of the period over which those customers will receive benefits from our current portfolio of services. During 2014, we began to sell go-live and training support services separate from the required implementation services. Go-live and training support services can be purchased by the customer from us or third-party vendors, and therefore, have stand-alone value and are recognized upon delivery of service. When we made this change, we began to include the fees associated with the required implementation services in our ongoing monthly rate; therefore, they are being recognized ratably over the customer life. Previously deferred revenue balances related to implementation services that were billed upfront and did not have stand-alone value will continue to be amortized over those remaining customer lives. Certain expenses related to the implementation go-live and training of a customer, such as out-of-pocket travel, are typically reimbursed by the customer. This is accounted for as both revenue and expense in the period the cost is incurred. Other revenue consists primarily of tenant revenue which is straight-lined over the term of the lease.
Direct Operating Expense	Direct Operating Expense – Direct operating expense consists primarily of compensation expense (including stock-based compensation) related to personnel who provide services, including implementation of clients, costs associated with our business partner outsourcing arrangements and clearing house, and claim processing costs. We expense implementation costs as incurred. We include in direct operating expense all service costs incurred to fulfill our customer contracts. Direct operating expense also includes costs associated with third-party tenant and other non-core revenue. Direct operating expense does not include allocated amounts for rent, occupancy costs, depreciation, or amortization, except for amortization related to certain purchased intangible assets.
Research and Development Expense	Research and Development Expense – Research and development expense consists primarily of compensation expense (including stock-based compensation) for research and development employees and consulting fees for third-party developers. All such costs are expensed as incurred, except for certain internal use software costs, which may be capitalized (refer to Note 6 – Capitalized Software Costs). Research and development expense does not include allocated amounts for rent, occupancy costs, depreciation, or amortization.
Stock-Based Compensation	Stock-Based Compensation – We account for share-based awards, including shares issued under employee stock purchase plans, stock options, and restricted stock units with compensation cost measured using the fair value of the awards issued. We use the Black-Scholes option pricing model to value share-based awards and determine the related compensation expense. The assumptions used in calculating the fair value of share-based awards represent management’s best estimates. We generally issue previously unissued shares for the exercise of stock options; however, we may reissue previously acquired treasury shares to satisfy these awards in the future. Certain employees have received awards for which the ultimate number of shares that will be subject to vesting is dependent upon the achievement of certain financial targets for the year. Such determination is not made until the award’s vesting determination date, which is the date our fiscal year financial statements are available. The award is initially recorded at the maximum attainable number of shares that is most likely to be subject to vesting based on available financial forecasts as of the date of grant. This amount is adjusted on a quarterly basis as new financial forecasts become available. Stock‑based compensation expense for these awards is recorded over the requisite service period, generally four years. Such awards generally vest ratably over four years from the vesting determination date.
Advertising Expenses	Advertising Expenses – Advertising expenses are expensed as incurred and are included in selling and marketing expense in the Consolidated Statements of Income.
Cash and Cash Equivalents	Cash and Cash Equivalents – We consider all highly liquid investments with an original or remaining maturity from the Company’s date of purchase of 90 days or less to be cash equivalents.
Investments	Investments – Management determines the appropriate classification of investments at the time of purchase based upon management’s intent with regard to such investments. Our convertible notes receivable from privately-held companies are accounted for as available-for-sale investments which are carried at cost, which we believe approximates fair value. Upon conversion, if any, we assess whether such equity investments should be accounted for on a cost basis or equity method, depending on whether we believe we have significant influence over the investee.
Concentrations of Credit Risk	Concentrations of Credit Risk – Financial instruments that potentially subject us to concentrations of credit risk are cash equivalents, investments, derivatives, notes receivables, and accounts receivable. We attempt to limit our credit risk associated with cash equivalents and investments by investing and/or depositing in highly-rated corporate and financial institutions, and engaging with highly-rated financial institutions as counterparties to our derivative transactions. With respect to customer accounts receivable, we manage our credit risk by performing ongoing credit evaluations of our customers.
Accounts Receivable	Accounts Receivable – Accounts receivable represents unbilled amounts and amounts due from customers for business services. Accounts receivable are stated net of an allowance for uncollectible accounts, which is determined by establishing reserves for specific accounts and consideration of historical and estimated probable losses.
Property and Equipment	Property and Equipment – Property and equipment are stated at cost less accumulated depreciation. Depreciation is calculated on a straight-line basis over the following estimated useful lives: Equipment, furniture, and fixtures 3-5 years Aircraft 20 years Buildings 30-40 years Building improvements 10-25 years Land improvements 10 years Leasehold improvements are depreciated using the straight-line method over the lesser of the useful life of the improvements or the applicable lease terms, excluding renewal periods. Costs associated with maintenance and repairs are expensed as incurred.
Capitalized Interest Cost	Capitalized Interest Cost – Interest costs related to major capital projects, specifically our corporate headquarters campus project and capitalized internal-use software costs, are capitalized until each underlying asset is placed into service. Capitalized interest is calculated by multiplying the effective interest rate of the outstanding debt by the qualifying costs. As the qualifying asset is placed into service, the qualifying asset and the related capitalized interest are amortized over the useful life of the related asset.
Capitalized Software Costs	Capitalized Software Costs – We capitalize certain costs related to the development of athenaNet services and other internal-use software. Costs incurred during the application development phase are capitalized only when we believe it is probable the development will result in new or additional functionality. The types of costs capitalized during the application development phase include employee wages and stock-based compensation expense, as well as external contractor costs for individuals working on these projects. Costs related to the preliminary project stage and post-implementation activities are expensed as incurred. Internal-use software is amortized on a straight-line basis over its estimated useful life. The estimated useful life of the software is two to five years (refer to Note 6 – Capitalized Software Costs).
Long-Lived Assets	Long-Lived Assets – Long-lived assets to be held and used are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Determination of recoverability of long-lived assets is based on an estimate of undiscounted future cash flows resulting from the use of the asset and its eventual disposition, as compared with the asset carrying value. Measurement of an impairment loss for long-lived assets that management expects to hold and use is based on the fair value of the asset. Long-lived assets to be disposed of are reported at the lower of carrying amount or fair value, less costs to sell.
Goodwill	Goodwill – Goodwill is recorded as the difference, if any, between the aggregate consideration paid for an acquisition and the fair value of the identifiable net tangible and intangible assets acquired. Goodwill is not amortized but is evaluated for impairment annually or more frequently if indicators of impairment are present or changes in circumstances suggest that impairment may exist. We evaluate the carrying value of our goodwill annually on November 30. The first step of the goodwill impairment test compares the fair value of the reporting unit with its carrying amount, including goodwill. If the fair value of our reporting unit exceeds its carrying amount, the goodwill of the reporting unit is not considered impaired. If the carrying amount of our reporting unit exceeds its fair value, the second step of the goodwill impairment test is performed to measure the amount of impairment loss, if any. The second step of the goodwill impairment test compares the implied fair value of the affected reporting unit’s goodwill with the carrying value of that goodwill.
Purchased Intangibles Assets	Purchased Intangible Assets – Purchased intangible assets consist of technology, a physician network, content, a trade name and trademark, customer backlog, non-compete agreements, customer relationships, above market leases, leases in place, and an indefinite-lived license related to the development of our headquarters' campus, most of which were acquired in connection with business acquisitions, and are amortized over their estimated useful lives based on the pattern of economic benefit expected from each asset. We concluded for certain purchased intangible assets that the pattern of economic benefit approximated the straight-line method, and therefore, the use of the straight-line method was appropriate, as the majority of the cash flows will be recognized ratably over the estimated useful lives and there is no degradation of the cash flows over time.
Deferred Rent	Deferred Rent – Deferred rent consists of rent escalation, tenant improvement allowances and other incentives received from landlords related to the operating leases for our facilities. Rent escalation represents the difference between actual operating lease payments due and straight-line rent expense, which we record over the term of the lease. The excess is recorded as a deferred credit in the early periods of the lease, when cash payments are generally lower than straight-line rent expense, and is reduced in the later periods of the lease when payments begin to exceed the straight-line expense. Tenant allowances from landlords for tenant improvements are generally comprised of cash received from the landlord or paid on our behalf as part of the negotiated terms of the lease. These tenant improvement allowances and other incentives are recorded when realizable as deferred rent and are amortized as a reduction of periodic rent expense, over the term of the applicable lease.
Deferred Revenue	Deferred Revenue – Deferred revenue primarily consists of billings or payments received in advance of the revenue recognition criteria being met. Deferred revenue includes amounts associated with multiple element arrangements associated with sponsored clinical information and decision support services which are recognized based upon contractual deliverables, and previously, deferred implementation services fees which will continue to be recognized as revenue ratably over the longer of the life of the agreement or the expected customer life, which is currently estimated to be 12 years. Deferred revenue that will be recognized during the succeeding 12-month period is recorded as current deferred revenue and the remaining portion is recorded as non-current.
Preferred and Common Stock	Preferred Stock – Our Board of Directors has the authority, without further action by stockholders, to issue up to 5,000 shares of preferred stock in one or more series. Our Board of Directors may designate the rights, preferences, privileges, and restrictions of the preferred stock, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preference, and number of shares constituting any series or the designation of any series. The issuance of preferred stock could have the effect of restricting dividends on our common stock, diluting the voting power of our common stock, impairing the liquidation rights of our common stock, or delaying or preventing a change in control. The ability to issue preferred stock could delay or impede a change in control. As of December 31, 2015 and 2014 , no shares of preferred stock were outstanding. Common Stock – Common stockholders are entitled to one vote per share and dividends, when declared by the Board of Directors, subject to any preferential rights of preferred stockholders.
Business Combinations	Business Combinations – We apply business combination accounting when we acquire control over a business. Business combinations are accounted for at fair value. The associated acquisition costs are expensed as incurred and recorded in general and administrative expenses; non-controlling interests, if any, are reflected at fair value at the acquisition date; in-process research and development, if any, is recorded at fair value as an intangible asset at the acquisition date; restructuring costs associated with a business combination are expensed; contingent consideration is measured at fair value at the acquisition date, with changes in the fair value after the acquisition date affecting earnings; changes in deferred tax asset valuation allowances and income tax uncertainties after the measurement period affect income tax expense; and goodwill is determined as the excess of the fair value of the consideration conveyed in the acquisition over the fair value of the net assets acquired. The accounting for business combinations requires estimates and judgments as to expectations for future cash flows of the acquired business, and the allocation of those cash flows to identifiable intangible assets, in determining the estimated fair value for assets and liabilities acquired. The fair values assigned to tangible and intangible assets acquired and liabilities assumed, are based on management’s estimates and assumptions, including valuations that utilize customary valuation procedures and techniques. If the actual results differ from the estimates and judgments used in these estimates, the amounts recorded in the financial statements could result in a possible impairment of the intangible assets and goodwill, or require acceleration of the amortization expense of finite-lived intangible assets. The results of the acquired businesses’ operations are included in the Consolidated Statements of Income of the combined entity beginning on the date of acquisition. We have applied this acquisition method to the transaction described in Note 2 – Business Combinations.
Income Taxes	Income Taxes – Deferred tax assets and liabilities relate to temporary differences between the financial reporting and income tax bases of assets and liabilities and are measured using enacted tax rates and laws expected to be in effect at the time of their reversal. A valuation allowance is established to reduce net deferred tax assets if, based on the available positive and negative evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. In making such determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax planning strategies, and recent financial results. We recognize a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Our income tax positions must meet a more-likely-than-not recognition threshold at the balance sheet date to be recognized in the related period. Our policy is to record interest and penalties related to unrecognized tax benefits in income tax expense.
Sales and Use Taxes	Sales and Use Taxes – Our services are subject to sales and use taxes in certain jurisdictions. Our contractual agreements with customers provide that payment of any sales or use tax assessments is the responsibility of the customer. In certain jurisdictions, sales taxes are collected from the customer and remitted to the respective agencies. These taxes are recorded on a net basis and excluded from revenue and expense in our financial statements as presented.
Incentives Received from Governmental Bodies	Incentives Received from Governmental Bodies – From time to time, we receive incentives from various government agencies and programs. We account for the portion of the credits that are expected to be used as grants by reducing general and administrative expense. Credits which are expected to be used to reduce general and administrative expense are recognized when the requirements to earn the credits have been met.
Foreign Currency Translation	Foreign Currency Translation – The financial position and results of operations of our foreign subsidiary are measured using local currency as the functional currency. Assets and liabilities are translated at the rate of exchange in effect at the end of each reporting period. Revenues and expenses are translated at the average exchange rate for the period. Foreign currency translation gains and losses are recorded within other comprehensive (loss) income.
Employee Benefit Plan	Employee Benefit Plan – We sponsor a 401(k) retirement savings plan (the “401(k) Plan”), under which eligible employees may contribute, on a pre-tax basis, specified percentages of their compensation, subject to maximum aggregate annual contributions imposed by the Internal Revenue Code of 1986. All employee contributions are allocated to the employee’s individual account and are invested in various investment options as directed by the employee. Employees’ cash contributions are fully vested and non-forfeitable. We may make a discretionary contribution in any year, subject to authorization by our Board of Directors.
New Accounting Pronouncements	New Accounting Pronouncements – In November 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2015-17, Balance Sheet Classification of Deferred Taxes , which will require entities to present all deferred tax assets (“DTAs”) and deferred tax liabilities (“DTLs”) as non-current on the balance sheet. This guidance is effective for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. Early adoption is permitted, and entities may choose whether to adopt this update prospectively or retrospectively. We have evaluated ASU 2015-17 and determined that its adoption will not have a material effect on our financial position or earnings. On December 31, 2015, we elected to adopt ASU 2015-17 and change our method of classifying DTAs and DTLs as either current or non-current to classifying all DTAs and DTLs as non-current, and have chosen to apply a prospective method. Prior balance sheets were not retrospectively adjusted. In September 2015, the FASB issued ASU 2015-16, Simplifying the Accounting for Measurement-Period Adjustments , that eliminates the requirement to restate prior period financial statements for measurement period adjustments. The new guidance requires that the cumulative impact of a measurement period adjustment (including the impact on prior periods) be recognized in the reporting period in which the adjustment is identified. The new standard should be applied prospectively to measurement period adjustments that occur after the effective date. This guidance is effective for public companies for interim and annual periods beginning after December 15, 2015. Early adoption is permitted for all entities. We have evaluated ASU 2015-16 and determined that its adoption will not have a material effect on our financial position or earnings. In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance , which changes the presentation of debt issuance costs in financial statements. Under this guidance, an entity will present such costs in the balance sheet as a reduction of the related debt liability rather than as an asset. This guidance is effective for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted for all entities for financial statements that have not been previously issued. We have evaluated ASU 2015-03 and determined that its adoption will not have a material effect on our financial position or earnings. On December 31, 2015, we elected to adopt ASU 2015-03 and change our method of classifying debt issuance costs whereby we will include debt issuance costs as a reduction to the related debt liability. The guidance was applied on a retrospective basis as prior balance sheets were adjusted. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers . This standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. In addition, ASU 2014-09 provides guidance on accounting for certain revenue-related costs including, but not limited to, when to capitalize costs associated with obtaining and fulfilling a contract. ASU 2014-09 provides companies with two implementation methods. Companies can choose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). This guidance was effective for annual reporting periods beginning after December 15, 2016. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers . The amendments in this ASU defer the effective date of ASU 2014-09. Public companies should apply the guidance in ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. We continue to evaluate the expected impact of this new guidance and available adoption methods.

NATURE OF OPERATIONS AND SUMM23

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Available-for-sale Securities	We had the following available-for-sale equity securities as of December 31, 2014 : Cost Gross Unrealized Gain Fair Value Marketable equity securities $ 1,100 $ 39,850 $ 40,950
Activity in the Allowance for Doubtful Accounts	Activity in the allowance for doubtful accounts is as follows: Years Ended December 31, 2015 2014 2013 Beginning balance $ 557 $ 1,691 $ 1,771 Provision 692 (769 ) 791 Write-offs (529 ) (365 ) (871 ) Ending balance $ 720 $ 557 $ 1,691
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following: Years Ended December 31, 2015 2014 2013 Prepaid expenses $ 17,882 $ 11,578 $ 10,006 Other receivables 12,294 10,599 6,715 Prepaid expenses and other current assets $ 30,176 $ 22,177 $ 16,721
Accrued Expenses	Accrued expenses consist of the following: As of December 31, 2015 2014 Accrued bonus $ 59,006 $ 38,938 Accrued vacation 9,826 8,106 Accrued payroll 9,386 19,846 Accrued commissions 9,904 4,878 Accrued compensation expenses $ 88,122 $ 71,768 Other accrued liabilities $ 42,636 $ 31,162 Accrued property and equipment additions 8,816 5,871 Accrued expenses $ 51,452 $ 37,033

NET INCOME (LOSS) PER SHARE (Ta

NET INCOME (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Income (Loss) per Share	The following table reconciles the weighted average shares outstanding for basic and diluted net income (loss) per share for the periods indicated: Years Ended December 31, 2015 2014 2013 Net income (loss) $ 14,027 $ (3,119 ) $ 2,594 Weighted average shares used in computing basic net income (loss) per share 38,611 37,862 36,856 Net income (loss) per share – Basic $ 0.36 $ (0.08 ) $ 0.07 Net income (loss) $ 14,027 $ (3,119 ) $ 2,594 Weighted average shares used in computing basic net income (loss) per share 38,611 37,862 36,856 Effect of dilutive securities 1,014 — 1,401 Weighted average shares used in computing diluted net income (loss) per share 39,625 37,862 38,257 Net income (loss) per share – Diluted $ 0.35 $ (0.08 ) $ 0.07

FAIR VALUE OF FINANCIAL INSTR25

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents information about our financial assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2015 and December 31, 2014 , and indicates the fair value hierarchy of the valuation techniques we utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities, and fair values determined by Level 2 inputs utilize quoted prices (unadjusted) in inactive markets for identical assets or liabilities obtained from readily available pricing sources for similar instruments. The fair values determined by Level 3 inputs are unobservable values which are supported by little or no market activity. It is our policy to recognize transfers between levels of the fair value hierarchy, if any, at the end of the reporting period; however, there have been no such transfers during any of the periods presented. Fair Value Measurements as of December 31, 2015, Using Level 1 Level 2 Level 3 Total Cash and cash equivalents: Money market $ 10,006 $ — $ — $ 10,006 Debt Securities: MDP Accelerator portfolio $ — $ — $ 1,250 $ 1,250 Total assets $ 10,006 $ — $ 1,250 $ 11,256 Interest rate swap liability (a) $ — $ (210 ) $ — $ (210 ) Total liabilities $ — $ (210 ) $ — $ (210 ) Fair Value Measurements as of December 31, 2014, Using Level 1 Level 2 Level 3 Total Available-for-sale investments: Marketable equity securities $ 40,950 $ — $ — $ 40,950 Debt Securities: MDP Accelerator portfolio $ — $ — $ 750 $ 750 Total assets $ 40,950 $ — $ 750 $ 41,700 Interest rate swap liability (b) $ — $ (244 ) $ — $ (244 ) Total liabilities $ — $ (244 ) $ — $ (244 ) (a) Recorded in other short-term liabilities on the Consolidated Balance Sheets. (b) Recorded in other long-term liabilities on the Consolidated Balance Sheets.
Reconciliations for Fair Values of Financial Instruments Determined by Level 3	The following table presents our financial instruments measured at fair value using unobservable inputs (Level 3) as of the years ended December 31, 2015 and 2014 : Fair Value Measurements Using Unobservable Inputs (Level 3) Year Ended December 31, 2015 Year Ended December 31, 2014 Balance, beginning of period $ 750 $ — Conversion (250 ) — Additions 750 750 Balance, end of period $ 1,250 $ 750

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consists of the following: Years Ended December 31, 2015 2014 Equipment $ 113,221 $ 93,583 Furniture and fixtures 25,152 14,760 Leasehold improvements 32,534 18,113 Aircraft 15,054 15,054 Building 131,746 131,746 Building improvements 81,163 49,671 Land 23,059 23,059 Land improvements 5,893 4,339 Total property and equipment, at cost 427,822 350,325 Accumulated depreciation (115,965 ) (96,416 ) Construction in progress 9,667 17,643 Property and equipment, net $ 321,524 $ 271,552

CAPITALIZED SOFTWARE COSTS (Tab

CAPITALIZED SOFTWARE COSTS (Tables)	12 Months Ended
	Dec. 31, 2015
Research and Development [Abstract]
Schedule of Capitalized Software	Capitalized software consisted of the following: Years ended December 31, 2015 2014 Capitalized internal-use software development costs $ 114,484 $ 72,666 Acquired third party software licenses for internal use 25,710 15,873 Total gross capitalized software for internal-use 140,194 88,539 Accumulated amortization (61,603 ) (34,972 ) Capitalized internal-use software in process 28,926 3,007 Total capitalized software costs $ 107,517 $ 56,574

GOODWILL AND PURCHASED INTANG28

GOODWILL AND PURCHASED INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table summarizes the activity related to the carrying value of our goodwill during the years ended December 31, 2015 and 2014 : Gross balance as of January 1, 2014 $ 198,049 Gross balance as of December 31, 2014 $ 198,049 Goodwill recorded in connection with the acquisition of Razor Insights, LLC 31,108 Gross balance as of December 31, 2015 $ 229,157
Schedule of Acquired Finite-Lived Intangible Assets by Major Class	ntangible assets acquired as of December 31, 2015 and 2014 are as follows: December 31, 2015 Gross Accumulated Amortization Net Developed technology $ 13,500 $ (9,575 ) $ 3,925 Customer relationships 25,434 (12,100 ) 13,334 Doctor network 104,000 (15,196 ) 88,804 Drug information content 10,000 (5,608 ) 4,392 Trade name 11,500 (3,224 ) 8,276 Trademark 100 (2 ) 98 Above market leases 2,967 (2,449 ) 518 Leases in place 15,557 (8,892 ) 6,665 Total $ 183,058 $ (57,046 ) $ 126,012 December 31, 2014 Gross Accumulated Amortization Net Developed technology $ 9,721 $ (6,294 ) $ 3,427 Customer relationships 21,434 (9,555 ) 11,879 Doctor network 104,000 (9,792 ) 94,208 Drug information content 10,000 (3,608 ) 6,392 Trade name 11,500 (2,074 ) 9,426 Non-compete agreement 1,178 (873 ) 305 Above market leases 3,016 (916 ) 2,100 Leases in place 19,695 (8,065 ) 11,630 Total $ 180,544 $ (41,177 ) $ 139,367
Schedule of Finite Lived Intangible Assets Future Amortization Expense	Estimated amortization expense, based upon our intangible assets at December 31, 2015 , is as follows: Year ending December 31, Amount 2016 20,290 2017 15,872 2018 14,597 2019 13,993 2020 12,650 Thereafter 48,610 Total $ 126,012

OPERATING LEASES AND OTHER CO29

OPERATING LEASES AND OTHER COMMITMENTS (Tables)	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Future minimum lease payments under non-cancelable operating leases as of December 31, 2015 are as follows: Year ending December 31, Future Rent Payments 2016 $ 13,524 2017 14,060 2018 13,881 2019 13,388 2020 12,462 Thereafter 86,333 Total minimum lease payments $ 153,648

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt	Future principal payments of the unsecured term loan facility at December 31, 2015 were as follows: Amount 2016 $ 11,250 2017 15,000 2018 20,625 2019 28,125 2020 225,000 Total $ 300,000 Less current portion 11,250 Long-term portion $ 288,750
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The fair value of the interest rate swap recognized in other short-term liabilities and in OCI was as follows: Fair Value Effective Date Notional Amount Fixed Rate Maturity December 31, 2015 December 31, 2014 August 31, 2013 120,000 0.8396 % August 31, 2016 $ (210 ) $ (244 )

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	Total stock-based compensation expense for the years ended December 31, 2015, 2014, and 2013 was as follows: Year Ended December 31, 2015 2014 2013 Stock-based compensation charged to: Direct operating $ 14,558 $ 12,009 $ 7,778 Selling and marketing 18,457 14,581 12,057 Research and development 8,956 7,221 4,238 General and administrative 22,163 21,747 18,575 Total stock-based compensation expense $ 64,134 $ 55,558 $ 42,648
Schedule of Share-based Compensation, Stock Options, Activity	The following table presents the stock option activity for the year ended December 31, 2015 : Shares Weighted- Weighted- Aggregate Outstanding – January 1, 2015 1,850 $ 65.14 Granted 278 129.25 Exercised (436 ) 37.79 Forfeited (134 ) 126.88 Outstanding – as of December 31, 2015 1,558 78.94 5.8 $ 132,465 Exercisable – as of December 31, 2015 1,075 $ 57.50 4.9 $ 112,311 Vested and expected to vest as of December 31, 2015 1,482 $ 76.04 5.7 $ 129,955 Weighted-average fair value of options granted for the year ended December 31, 2015 $ 49.29
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The following table illustrates the range of assumptions used to compute stock-based compensation expense for awards granted: Year Ended December 31, 2015 2014 2013 Risk-free interest rate 1.06% - 1.57% .66% - 1.67% .35% - .75% Expected dividend yield —% —% —% Expected option term (years) 3.0 - 5.0 3.0 - 5.0 3.0 - 5.0 Expected stock volatility 40% - 42% 46% - 47% 41% - 45%
Schedule of Nonvested Restricted Stock Units Activity	The following table presents the restricted stock unit activity for the year ended December 31, 2015 : Shares Weighted- Outstanding – January 1, 2015 1,210 $ 124.65 Granted 576 132.31 Vested (483 ) 103.31 Forfeited (150 ) 101.56 Outstanding – as of December 31, 2015 1,153 $ 136.06

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Components of Income (Loss) before Income Tax	The components of income (loss) before income tax (provision) benefit for the years ended December 31, 2015, 2014, and 2013 were as follows: 2015 2014 2013 U.S. $ 17,130 $ (4,579 ) $ 1,536 Non-U.S. 1,756 715 695 Total $ 18,886 $ (3,864 ) $ 2,231
Current Foreign Tax Expense (Benefit)	The components of our income tax (provision) benefit for the years ended December 31, 2015, 2014, and 2013 were as follows: 2015 2014 2013 Current Provision: Federal $ (11,810 ) $ (9,656 ) $ (4,225 ) State (764 ) (884 ) (1,495 ) Foreign (827 ) (385 ) (961 ) (13,401 ) (10,925 ) (6,681 ) Deferred Benefit: Federal 5,787 10,695 5,291 State 2,565 906 1,753 Foreign 190 69 — 8,542 11,670 7,044 Total income tax (provision) benefit $ (4,859 ) $ 745 $ 363
Schedule of Deferred Tax Assets and Liabilities	The components of our deferred income taxes as of December 31, 2015 and 2014 were as follows: 2015 2014 Deferred tax assets: State net operating loss carryforward $ 1,898 $ 1,694 Research and development tax credits 3,644 3,328 Allowances for accounts receivable 362 1,168 Deferred rent obligation 12,073 7,555 Stock compensation 29,306 25,264 Other accrued liabilities 2,860 2,223 Deferred revenue 20,107 17,797 Other 1,557 1,473 Total gross deferred tax assets 71,807 60,502 Valuation allowance (4,041 ) (3,420 ) Total deferred tax assets 67,766 57,082 Deferred tax liabilities: Intangible assets (34,599 ) (40,463 ) Capitalized software (23,624 ) (15,769 ) Property and equipment (10,502 ) (4,621 ) Investments 80 (14,913 ) Total deferred tax liabilities (68,645 ) (75,766 ) Net deferred tax liabilities $ (879 ) $ (18,684 )
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the federal statutory income tax rate to our effective income tax rate is as follows for the years ended December 31, 2015, 2014, and 2013 : 2015 2014 2013 Income tax computed at federal statutory tax rate 35 % 35 % 35 % State taxes, net of federal benefit 7 % 6 % (6 )% Research and development credits (32 )% 86 % (98 )% Permanent differences 13 % (87 )% 20 % Valuation allowance 3 % (21 )% 33 % Effective income tax rate 26 % 19 % (16 )%
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible	A reconciliation of the beginning and ending amount of uncertain tax benefits is as follows: 2015 2014 2013 Beginning uncertain tax benefits $ 5,813 $ 4,851 $ 1,761 Prior year – decreases — (79 ) (537 ) Prior year – increases 508 887 501 Acquired balances — — 2,339 Current year - decreases (454 ) (212 ) — Current year – increases 1,797 366 787 Ending uncertain tax benefits $ 7,664 $ 5,813 $ 4,851

QUARTERLY FINANCIAL INFORMATI33

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Selected quarterly financial information follows for the year ended December 31, 2015 : First Quarter Second Quarter Third Quarter Fourth Quarter Year Revenue: Business services $ 197,763 $ 215,403 $ 224,990 $ 247,919 $ 886,075 Implementation and other 8,671 9,291 11,078 9,613 38,653 Total revenue 206,434 224,694 236,068 257,532 924,728 Expense: Direct operating 84,557 89,899 94,850 97,253 366,559 Selling and marketing 53,365 54,413 55,927 66,196 229,901 Research and development 23,728 24,387 22,560 23,579 94,254 General and administrative 36,212 36,103 34,778 37,484 144,577 Depreciation and amortization 20,352 22,101 24,763 26,277 93,493 Total expense 218,214 226,903 232,878 250,789 928,784 Operating (loss) income (11,780 ) (2,209 ) 3,190 6,743 (4,056 ) Other (expense) income: Interest expense (1,059 ) (1,513 ) (1,620 ) (1,604 ) (5,796 ) Other income 44 21,081 7,590 23 28,738 Total other (expense) income (1,015 ) 19,568 5,970 (1,581 ) 22,942 (Loss) income before income tax benefit (provision) (12,795 ) 17,359 9,160 5,162 18,886 Income tax benefit (provision) 3,963 (8,010 ) (3,365 ) 2,553 (4,859 ) Net (loss) income $ (8,832 ) $ 9,349 $ 5,795 $ 7,715 $ 14,027 Net (loss) income per share – Basic $ (0.23 ) $ 0.24 $ 0.15 $ 0.20 $ 0.36 Net (loss) income per share – Diluted $ (0.23 ) $ 0.24 $ 0.15 $ 0.19 $ 0.35 Weighted average shares used in computing net (loss) income per share: Basic 38,278 38,574 38,714 38,873 38,611 Diluted 38,278 39,340 39,536 39,809 39,625 Selected quarterly financial information follows for the year ended December 31, 2014 : First Second Third Fourth Year Revenue: Business services $ 154,502 $ 175,949 $ 179,711 $ 201,072 $ 711,234 Implementation and other 8,533 9,973 10,717 12,142 41,365 Total revenue 163,035 185,922 190,428 213,214 752,599 Expense: Direct operating 72,148 74,774 79,343 76,274 302,539 Selling and marketing 43,227 50,722 45,206 50,533 189,688 Research and development 15,155 16,417 18,087 19,802 69,461 General and administrative 29,357 30,443 31,800 33,592 125,192 Depreciation and amortization 14,249 15,186 17,258 18,071 64,764 Total expense 174,136 187,542 191,694 198,272 751,644 Operating (loss) income (11,101 ) (1,620 ) (1,266 ) 14,942 955 Other (expense) income: Interest expense (1,265 ) (1,275 ) (1,244 ) (911 ) (4,695 ) Other income (171 ) (6 ) 26 27 (124 ) Total other (expense) income (1,436 ) (1,281 ) (1,218 ) (884 ) (4,819 ) (Loss) income before income tax benefit (provision) (12,537 ) (2,901 ) (2,484 ) 14,058 (3,864 ) Income tax benefit (provision) 4,482 739 853 (5,329 ) 745 Net (loss) income $ (8,055 ) $ (2,162 ) $ (1,631 ) $ 8,729 $ (3,119 ) Net (loss) income per share – Basic $ (0.21 ) $ (0.06 ) $ (0.04 ) $ 0.23 $ (0.08 ) Net (loss) income per share – Diluted $ (0.21 ) $ (0.06 ) $ (0.04 ) $ 0.22 $ (0.08 ) Weighted average shares used in computing net (loss) income per share: Basic 37,484 37,860 37,999 38,097 37,862 Diluted 37,484 37,860 37,999 39,040 37,862

NATURE OF OPERATIONS AND SUMM34

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Narrative (Details)	12 Months Ended
	Dec. 31, 2015USD ($)Vote / sharesSeriessourceSegmentshares	Dec. 31, 2014USD ($)Segmentshares	Dec. 31, 2013USD ($)
Significant Accounting Policies [Line Items]
Number of operating segments | Segment	1	1
Number of revenue sources | source	2
Term of service contracts	1 year
Period for notice of termination of agreement without cause	90 days
Deferred revenue, estimated period of recognition (in years)	12 years
Requisite service period	4 years
Options granted vesting period	4 years
Advertising expense	$ 28,100,000	$ 15,500,000	$ 14,200,000
Impairment gain (loss) for long lived assets	0	0	0
Impairment losses recognized	$ 0	$ 0	0
Preferred stock, shares authorized (shares) | shares	5,000,000	5,000,000
Preferred stock, shares outstanding (shares) | shares	0	0
Votes per share entitled to common stockholders | Vote / shares	1
Related party transaction, total expense	$ 23,600,000	$ 11,300,000	1,500,000
Related party transaction, total payable	2,300,000	1,300,000
Proceeds from incentive programs	$ 4,100,000	1,200,000
Aircraft
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	20 years
Land improvements
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	10 years
Minimum
Significant Accounting Policies [Line Items]
Number of series (more than) | Series	1
Minimum | Developed technology
Significant Accounting Policies [Line Items]
Estimated useful life of the software (in years)	2 years
Minimum | Furniture fixtures and equipment
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	3 years
Minimum | Building
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	30 years
Minimum | Building improvements
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	10 years
Maximum | Developed technology
Significant Accounting Policies [Line Items]
Estimated useful life of the software (in years)	5 years
Maximum | Furniture fixtures and equipment
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	5 years
Maximum | Building
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	40 years
Maximum | Building improvements
Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment (in years)	25 years
Epocrates
Significant Accounting Policies [Line Items]
Term of service contracts	1 year
Epocrates | Minimum
Significant Accounting Policies [Line Items]
Period for redeemable license code subscription	6 months
Epocrates | Maximum
Significant Accounting Policies [Line Items]
Period for redeemable license code subscription	12 months
Defined Contribution Pension Plan
Significant Accounting Policies [Line Items]
Defined contribution plan, employer discretionary contribution amount	$ 5,300,000	4,500,000	$ 3,200,000
Marketable equity securities
Significant Accounting Policies [Line Items]
Available-for-sale investments:	$ 0	$ 40,950,000

NATURE OF OPERATIONS AND SUMM35

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Schedule of Available for Sale Securities (Details) - Marketable equity securities - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost		$ 1,100,000
Gross Unrealized Gain		39,850,000
Fair Value	$ 0	$ 40,950,000

NATURE OF OPERATIONS AND SUMM36

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Activity in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$ 557	$ 1,691	$ 1,771
Provision	692	(769)	791
Write-offs	(529)	(365)	(871)
Ending balance	$ 720	$ 557	$ 1,691

NATURE OF OPERATIONS AND SUMM37

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued bonus	$ 59,006	$ 38,938
Accrued vacation	9,826	8,106
Accrued payroll	9,386	19,846
Accrued commissions	9,904	4,878
Accrued compensation expenses	88,122	71,768
Other Accrued Liabilities, Current	42,636	31,162
Accrued property and equipment additions	8,816	5,871
Accrued expenses	$ 51,452	$ 37,033

NATURE OF OPERATIONS AND SUMM38

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Prepaid expenses	$ 17,882	$ 11,578	$ 10,006
Other receivables	12,294	10,599	6,715
Prepaid expenses and other current assets	$ 30,176	$ 22,177	$ 16,721

BUSINESS COMBINATIONS Narrative

BUSINESS COMBINATIONS Narrative (Details) - USD ($) $ in Thousands	Jan. 13, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill		$ 229,157	$ 198,049	$ 198,049
RazorInsights
Business Acquisition [Line Items]
Payments to acquire business, gross	$ 39,900
Measurement period adjustments	1,000
Fair value of assets acquired	8,900
Goodwill	31,100
Transaction costs associated with the acquisition	300
Technology-Based Intangible Assets | RazorInsights
Business Acquisition [Line Items]
Intangible assets acquired	7,000
Customer Relationships | RazorInsights
Business Acquisition [Line Items]
Intangible assets acquired	$ 4,000

NET INCOME (LOSS) PER SHARE Net

NET INCOME (LOSS) PER SHARE Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income (loss)	$ 7,715	$ 5,795	$ 9,349	$ (8,832)	$ 8,729	$ (1,631)	$ (2,162)	$ (8,055)	$ 14,027	$ (3,119)	$ 2,594
Weighted average shares used in computing basic net income (loss) per share (shares)	38,873	38,714	38,574	38,278	38,097	37,999	37,860	37,484	38,611	37,862	36,856
Net (loss) income per share - Basic (in dollars per share)	$ 0.20	$ 0.15	$ 0.24	$ (0.23)	$ 0.23	$ (0.04)	$ (0.06)	$ (0.21)	$ 0.36	$ (0.08)	$ 0.07
Effect of dilutive securities (shares)									1,014	0	1,401
Weighted average shares used in computing diluted net income (loss) per share (shares)	39,809	39,536	39,340	38,278	39,040	37,999	37,860	37,484	39,625	37,862	38,257
Net (loss) income per share - Diluted (in dollars per share)	$ 0.19	$ 0.15	$ 0.24	$ (0.23)	$ 0.22	$ (0.04)	$ (0.06)	$ (0.21)	$ 0.35	$ (0.08)	$ 0.07

NET INCOME (LOSS) PER SHARE Nar

NET INCOME (LOSS) PER SHARE Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013
Earnings Per Share [Abstract]
Options and restricted stock units which have an antidilutive effect (shares)	0.7	0.4

FAIR VALUE OF FINANCIAL INSTR42

FAIR VALUE OF FINANCIAL INSTRUMENTS Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate cash flow hedge gain (loss) reclassified to earnings, net	$ 0	$ 0
Gain (loss) on interest rate cash flow hedge ineffectiveness	0	0
Other Long Term Liabilities | Designated as Hedging Instrument | Interest Rate Swap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of swap recognized	210,000	244,000
Senior Credit Facility, 2015 | Unsecured Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amount outstanding on facility	300,000,000
Senior Credit Facility | Unsecured Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amount outstanding on facility		173,800,000
Senior Credit Facility | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amount outstanding on facility	$ 0	$ 35,000,000

FAIR VALUE OF FINANCIAL INSTR43

FAIR VALUE OF FINANCIAL INSTRUMENTS Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 11,256,000	$ 41,700,000
Interest rate swap liability	(210,000)	(244,000)
Total liabilities	(210,000)	(244,000)
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	10,006,000	40,950,000
Interest rate swap liability	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Interest rate swap liability	(210,000)	(244,000)
Total liabilities	(210,000)	(244,000)
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,250,000	750,000
Interest rate swap liability	0	0
Total liabilities	0	0
Marketable equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments:	0	40,950,000
Marketable equity securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments:		40,950,000
Marketable equity securities | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments:		40,950,000
Marketable equity securities | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments:		0
Marketable equity securities | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments:		0
Money market | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents:	10,006,000
Money market | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents:	10,006,000
Money market | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents:	0
Money market | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents:	0
MDP Accelerator portfolio | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities:	1,250,000	750,000
MDP Accelerator portfolio | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities:	0	0
MDP Accelerator portfolio | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities:	0	0
MDP Accelerator portfolio | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities:	$ 1,250,000	$ 750,000

FAIR VALUE OF FINANCIAL INSTR44

FAIR VALUE OF FINANCIAL INSTRUMENTS Reconciliations for Fair Values of Financial Instruments Determined by Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
MDP Accelerator portfolio
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 750	$ 0
Additions	750	750
Balance, end of period	1,250	750
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Conversion	$ (250)	$ 0

PROPERTY AND EQUIPMENT Narrativ

PROPERTY AND EQUIPMENT Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Capital leases	$ 0	$ 0
Property and equipment, depreciation expense	$ 40,100,000	$ 31,500,000	$ 25,500,000

PROPERTY AND EQUIPMENT Schedule

PROPERTY AND EQUIPMENT Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 427,822	$ 350,325
Accumulated depreciation	(115,965)	(96,416)
Construction in progress	9,667	17,643
Property and equipment, net	321,524	271,552
Equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	113,221	93,583
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	25,152	14,760
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	32,534	18,113
Aircraft
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	15,054	15,054
Building
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	131,746	131,746
Building improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	81,163	49,671
Land
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	23,059	23,059
Land improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 5,893	$ 4,339

CAPITALIZED SOFTWARE COSTS Narr

CAPITALIZED SOFTWARE COSTS Narrative (Details) $ in Thousands	Jan. 23, 2015USD ($)facility	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Business Acquisition [Line Items]
Capitalized software amortization expense		$ 53,400	$ 33,200	$ 18,000
Future amortization expense for software development, year one		20,290
Future amortization expense for software development, year two		15,872
Future amortization expense for software development, year three		14,597
Developed technology
Business Acquisition [Line Items]
Future amortization expense for software development, year one		54,000
Future amortization expense for software development, year two		22,500
Future amortization expense for software development, year three		$ 2,100
webOMR
Business Acquisition [Line Items]
Payments to acquire software	$ 22,000
Contingent consideration, value	$ 18,000
Collaboration agreement, term	2 years
Collaboration agreement, number of facilities provided as testing site | facility	1

CAPITALIZED SOFTWARE COSTS Sche

CAPITALIZED SOFTWARE COSTS Schedule of Capitalized Software (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total gross capitalized software for internal-use	$ 140,194	$ 88,539
Accumulated amortization	(61,603)	(34,972)
Capitalized internal-use software in process	28,926	3,007
Total capitalized software costs	107,517	56,574
Software Development
Property, Plant and Equipment [Line Items]
Total gross capitalized software for internal-use	114,484	72,666
Software Licenses
Property, Plant and Equipment [Line Items]
Total gross capitalized software for internal-use	$ 25,710	$ 15,873

GOODWILL AND PURCHASED INTANG49

GOODWILL AND PURCHASED INTANGIBLE ASSETS Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 24	$ 28.6	$ 17.9
Licensing Agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived license agreements	$ 0.2

GOODWILL AND PURCHASED INTANG50

GOODWILL AND PURCHASED INTANGIBLE ASSETS Schedule of Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Goodwill [Roll Forward]
Beginning gross balance	$ 198,049
Goodwill recorded during the period	31,108
Ending gross balance	$ 229,157

GOODWILL AND PURCHASED INTANG51

GOODWILL AND PURCHASED INTANGIBLE ASSETS Schedule of Acquired Finite-Lived Intangible Assets by Major Class (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	$ 183,058	$ 180,544
Accumulated Amortization	(57,046)	(41,177)
Net	126,012	139,367
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	13,500	9,721
Accumulated Amortization	(9,575)	(6,294)
Net	3,925	3,427
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	25,434	21,434
Accumulated Amortization	(12,100)	(9,555)
Net	13,334	11,879
Doctor network
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	104,000	104,000
Accumulated Amortization	(15,196)	(9,792)
Net	88,804	94,208
Drug information content
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	10,000	10,000
Accumulated Amortization	(5,608)	(3,608)
Net	4,392	6,392
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	11,500	11,500
Accumulated Amortization	(3,224)	(2,074)
Net	8,276	9,426
Trademark
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	100
Accumulated Amortization	(2)
Net	98
Non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Gross		1,178
Accumulated Amortization		(873)
Net		305
Above market leases
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	2,967	3,016
Accumulated Amortization	(2,449)	(916)
Net	518	2,100
Leases in place
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	15,557	19,695
Accumulated Amortization	(8,892)	(8,065)
Net	$ 6,665	$ 11,630

GOODWILL AND PURCHASED INTANG52

GOODWILL AND PURCHASED INTANGIBLE ASSETS Schedule of Finite Lived Intangible Assets Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
2,016	$ 20,290
2,017	15,872
2,018	14,597
2,019	13,993
2,020	12,650
Thereafter	48,610
Net	$ 126,012	$ 139,367

OPERATING LEASES AND OTHER CO53

OPERATING LEASES AND OTHER COMMITMENTS Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)location	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Leases [Abstract]
Number of locations under operating lease | location	4
Operating Leases, rent expense net | $	$ 9.8	$ 9.9	$ 5.5

OPERATING LEASES AND OTHER CO54

OPERATING LEASES AND OTHER COMMITMENTS Schedule of Future Minimum Rental Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2015USD ($)
Leases [Abstract]
2,016	$ 13,524
2,017	14,060
2,018	13,881
2,019	13,388
2,020	12,462
Thereafter	86,333
Total minimum lease payments	$ 153,648

DEBT Narrative (Details)

DEBT Narrative (Details) - USD ($)	May. 05, 2015	Dec. 31, 2015	Dec. 31, 2014	Aug. 31, 2013	May. 10, 2013
Interest Rate Swap | Designated as Hedging Instrument
Debt Instrument [Line Items]
Derivative, notional amount				$ 120,000,000
Derivative, fixed interest rate				0.8396%
Senior Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity					$ 325,000,000
Interest rate for facility		1.74%
Senior Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity					125,000,000
Long-term line of credit		$ 0	$ 35,000,000
Senior Credit Facility | Unsecured Debt
Debt Instrument [Line Items]
Current borrowing capacity					$ 200,000,000
Long-term line of credit			$ 173,800,000
Senior Credit Facility, 2015
Debt Instrument [Line Items]
Current borrowing capacity	$ 500,000,000
Financing fees	$ 1,000,000
Debt instrument, term	5 years
Senior Credit Facility, 2015 | Revolving Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity	$ 200,000,000
Additional borrowing capacity for Senior Credit Facility	100,000,000
Senior Credit Facility, 2015 | Unsecured Debt
Debt Instrument [Line Items]
Current borrowing capacity	300,000,000
Long-term line of credit		$ 300,000,000
Senior Credit Facility, 2013 | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term line of credit	$ 0
Federal Funds Effective Swap Rate | Senior Credit Facility, 2015
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
London Interbank Offered Rate (LIBOR) | Senior Credit Facility, 2015
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Minimum | Senior Credit Facility, 2015
Debt Instrument [Line Items]
Commitment fee percentage		0.20%
Maximum | Senior Credit Facility, 2015
Debt Instrument [Line Items]
Commitment fee percentage		0.40%

DEBT Schedule of Maturities of

DEBT Schedule of Maturities of Long Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Less current portion	$ 10,762	$ 14,550
Long-term portion	287,353	$ 157,822
Unsecured Debt | Senior Credit Facility
Line of Credit Facility [Line Items]
2,016	11,250
2,017	15,000
2,018	20,625
2,019	28,125
2,020	225,000
Total	300,000
Less current portion	11,250
Long-term portion	$ 288,750

DEBT Schedule of Derivative Ins

DEBT Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - Interest Rate Swap - Designated as Hedging Instrument - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Aug. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative, notional amount			$ 120,000,000
Derivative, fixed interest rate			0.8396%
Other Long Term Liabilities
Derivatives, Fair Value [Line Items]
Fair value of swap recognized	$ (210,000)	$ (244,000)

STOCK-BASED COMPENSATION Narrat

STOCK-BASED COMPENSATION Narrative (Details)	12 Months Ended
	Dec. 31, 2015USD ($)Installment$ / shares	Dec. 31, 2014USD ($)$ / shares	Dec. 31, 2013USD ($)$ / sharesshares	Dec. 31, 2012shares	Dec. 31, 2011shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization of capitalized stock-based compensation related to software development	$ 4,404,000	$ 2,258,000
Options granted vesting period	4 years
Options granted contractual term (in years)	4 years 11 months
Compensation expense	$ 64,134,000	55,558,000	$ 42,648,000
Unrecognized stock-based compensation expense, expected weighted-average period for recognition (in years)	2 years 1 month 6 days
Weighted average fair value of stock options granted | $ / shares	$ 49.29
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 11,600,000	11,700,000	$ 14,000,000
Amount of fair value of stock options and restricted stock units allocated to future services	$ 11,400,000	$ 16,500,000
Weighted average fair value of stock options granted | $ / shares	$ 49.29	$ 77.55	$ 38.09
Intrinsic value of shares purchased	$ 44,300,000	$ 53,500,000	$ 53,200,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of fair value of stock options and restricted stock units allocated to future services	$ 93,500,000
Unrecognized stock-based compensation expense, expected weighted-average period for recognition (in years)	2 years 8 months 12 days
Number of annual anniversary installments | Installment	4
Number of quarterly anniversary installments | Installment	4
Compensation expense, restricted stock	$ 51,000,000	$ 42,200,000	$ 27,400,000
Weighted average fair value of restricted units granted | $ / shares	$ 132.31	$ 181.81	$ 98.34
Intrinsic value of vested restricted stock units	$ 61,600,000	$ 78,500,000	$ 35,200,000
Stock Option Plan 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares reserved for issuance (shares) | shares			1,660,000	1,850,000	1,300,000
Multiplier of full value of awards (shares) | shares				1.66	1.3
Options granted vesting percentage per year	25.00%
Stock Option Plan 2007 | Management
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period	4 years
Stock Option Plan 2007 | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period	1 year
Options granted contractual term (in years)	5 years
Stock Option Plan 2007 | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period	4 years
Options granted contractual term (in years)	10 years
Employee Stock Purchase Plan (''2007 ESPP'')
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 1,500,000	1,700,000	$ 1,200,000
Employee stock purchase price, percentage of the closing price of common stock	85.00%
Incentive Stock Plans | Stock Option Plan 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of employees who has voting power of all classes of stock granted incentive stock option	10.00%
Percentage of exercise price of the fair value of the Company's common stock at the date of the grant	110.00%
Software Development Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation capitalized	$ 7,300,000	$ 4,700,000

STOCK-BASED COMPENSATION Schedu

STOCK-BASED COMPENSATION Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 64,134	$ 55,558	$ 42,648
Direct operating
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	14,558	12,009	7,778
Selling and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	18,457	14,581	12,057
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	8,956	7,221	4,238
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 22,163	$ 21,747	$ 18,575

STOCK-BASED COMPENSATION Sche60

STOCK-BASED COMPENSATION Schedule of Share-based Compensation, Stock Options, Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Shares
Beginning balance | shares	1,850
Granted | shares	278
Exercised | shares	(436)
Forfeited | shares	(134)
Outstanding – as of December 31, 2015 | shares	1,558
Exercisable – as of December 31, 2015 | shares	1,075
Vested and expected to vest as of December 31, 2015 | shares	1,482
Weighted- Average Exercise Price
Beginning balance	$ 65.14
Granted	129.25
Exercised	37.79
Forfeited	126.88
Ending balance	78.94
Exercisable – as of December 31, 2015	57.50
Vested and expected to vest as of December 31, 2015	76.04
Weighted-average fair value of options granted for the year ended December 31, 2015	$ 49.29
Weighted- Average Remaining Contractual Term (in years)
Outstanding – as of December 31, 2015	5 years 9 months
Vested and expected to vest as of December 31, 2015	4 years 11 months
Vested and expected to vest as of December 31, 2015	5 years 8 months 12 days
Aggregate Intrinsic Value
Outstanding – as of December 31, 2015 | $	$ 132,465
Exercisable – as of December 31, 2015 | $	112,311
Vested and expected to vest as of December 31, 2015 | $	$ 129,955

STOCK-BASED COMPENSATION Sche61

STOCK-BASED COMPENSATION Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	1.06%	0.66%	0.35%
Risk-free interest rate, maximum	1.57%	1.67%	0.75%
Expected dividend yield	0.00%	0.00%	0.00%
Expected stock volatility, minimum	40.00%	46.00%	41.00%
Expected stock volatility, maximum	42.00%	47.00%	45.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option term (years)	3 years	3 years	3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option term (years)	5 years	5 years	5 years

STOCK-BASED COMPENSATION Sche62

STOCK-BASED COMPENSATION Schedule of Nonvested Restricted Stock Units Activity (Details) - Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares
Beginning Balance	1,210,000
Granted	576,000
Vested	(483,000)
Forfeited	(150,000)
Ending Balance	1,153,000	1,210,000
Weighted- Average Grant Date Fair Value
Beginning Balance	$ 124.65
Granted	132.31	$ 181.81	$ 98.34
Vested	103.31
Forfeited	101.56
Ending Balance	$ 136.06	$ 124.65

INCOME TAXES Narrative (Details

INCOME TAXES Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Tax benefit realized from stock-based awards	$ 10,300,000	$ 9,900,000	$ 6,900,000
Unrecognized tax benefits	7,664,000	5,813,000	4,851,000	$ 1,761,000
Unrecognized tax benefits, if recognized, would impact effective tax rate	6,700,000
Unrecognized tax benefits, income tax penalties and interest expense	0	800,000
Unrecognized tax benefits, interest on income taxes accrued	1,200,000	1,200,000
Unrecognized tax benefits, accrued interest and penalties adjustment, foreign currency translation		300,000
Federal
Income Taxes [Line Items]
Decrease in current tax provision by utilizing operating loss carryforwards	12,900,000	9,900,000	$ 7,000,000
Operating loss carryforwards	85,600,000	73,600,000
Unrecognized tax benefits	100,000,000
R&D credits	$ 14,300,000
Federal | Minimum
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2,020
Federal | Maximum
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2,035
State
Income Taxes [Line Items]
Operating loss carryforwards	$ 67,900,000	67,700,000
Unrecognized tax benefits	33,400,000
R&D credits	6,700,000
Utilization of credits under the without method of accounting related to stock-based compensation	$ 4,100,000
State | Minimum
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2,018
State | Stock Based Compensation Expense
Income Taxes [Line Items]
Operating loss carryforwards	$ 29,200,000	$ 32,700,000

INCOME TAXES Components of Inco

INCOME TAXES Components of Income (Loss) before Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
U.S.									$ 17,130	$ (4,579)	$ 1,536
Non-U.S.									1,756	715	695
Income (loss) before income tax (provision) benefit	$ 5,162	$ 9,160	$ 17,359	$ (12,795)	$ 14,058	$ (2,484)	$ (2,901)	$ (12,537)	$ 18,886	$ (3,864)	$ 2,231

INCOME TAXES Current Foreign Ta

INCOME TAXES Current Foreign Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Provision:
Federal									$ (11,810)	$ (9,656)	$ (4,225)
State									(764)	(884)	(1,495)
Foreign									(827)	(385)	(961)
Current income tax benefit (provision), total									(13,401)	(10,925)	(6,681)
Deferred Benefit:
Federal									5,787	10,695	5,291
State									2,565	906	1,753
Foreign									190	69	0
Deferred income taxes									8,542	11,670	7,044
Total income tax (provision) benefit	$ 2,553	$ (3,365)	$ (8,010)	$ 3,963	$ (5,329)	$ 853	$ 739	$ 4,482	$ (4,859)	$ 745	$ 363

INCOME TAXES Schedule of Deferr

INCOME TAXES Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
State net operating loss carryforward	$ 1,898	$ 1,694
Research and development tax credits	3,644	3,328
Allowances for accounts receivable	362	1,168
Deferred rent obligation	12,073	7,555
Stock compensation	29,306	25,264
Other accrued liabilities	2,860	2,223
Deferred revenue	20,107	17,797
Other	1,557	1,473
Total gross deferred tax assets	71,807	60,502
Valuation allowance	(4,041)	(3,420)
Total deferred tax assets	67,766	57,082
Deferred tax liabilities:
Intangible assets	(34,599)	(40,463)
Capitalized software	(23,624)	(15,769)
Property and equipment	(10,502)	(4,621)
Investments	80	(14,913)
Deferred Income Tax Liabilities, Net	(68,645)	(75,766)
Total deferred tax liabilities	$ (879)	$ (18,684)

INCOME TAXES Schedule of Effect

INCOME TAXES Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Income tax computed at federal statutory tax rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	7.00%	6.00%	(6.00%)
Research and development credits	(32.00%)	86.00%	(98.00%)
Permanent differences	13.00%	(87.00%)	20.00%
Valuation allowance	3.00%	(21.00%)	33.00%
Effective income tax rate	26.00%	19.00%	(16.00%)

INCOME TAXES Summary of Positio

INCOME TAXES Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning uncertain tax benefits	$ 5,813	$ 4,851	$ 1,761
Prior year – decreases	0	(79)	(537)
Prior year – increases	508	887	501
Acquired balances	0	0	2,339
Current year - decreases	(454)	(212)	0
Current year – increases	1,797	366	787
Ending uncertain tax benefits	$ 7,664	$ 5,813	$ 4,851

QUARTERLY FINANCIAL INFORMATI69

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Business services	$ 247,919	$ 224,990	$ 215,403	$ 197,763	$ 201,072	$ 179,711	$ 175,949	$ 154,502	$ 886,075	$ 711,234	$ 563,237
Implementation and other	9,613	11,078	9,291	8,671	12,142	10,717	9,973	8,533	38,653	41,365	31,766
Total revenue	257,532	236,068	224,694	206,434	213,214	190,428	185,922	163,035	924,728	752,599	595,003
Expense:
Direct operating	97,253	94,850	89,899	84,557	76,274	79,343	74,774	72,148	366,559	302,539	238,672
Selling and marketing	66,196	55,927	54,413	53,365	50,533	45,206	50,722	43,227	229,901	189,688	149,488
Research and development	23,579	22,560	24,387	23,728	19,802	18,087	16,417	15,155	94,254	69,461	57,639
General and administrative	37,484	34,778	36,103	36,212	33,592	31,800	30,443	29,357	144,577	125,192	99,776
Depreciation and amortization	26,277	24,763	22,101	20,352	18,071	17,258	15,186	14,249	93,493	64,764	43,575
Total expense	250,789	232,878	226,903	218,214	198,272	191,694	187,542	174,136	928,784	751,644	589,150
Operating (loss) income	6,743	3,190	(2,209)	(11,780)	14,942	(1,266)	(1,620)	(11,101)	(4,056)	955	5,853
Other income (expense):
Interest expense	(1,604)	(1,620)	(1,513)	(1,059)	(911)	(1,244)	(1,275)	(1,265)	(5,796)	(4,695)	(3,905)
Other income	23	7,590	21,081	44	27	26	(6)	(171)	28,738	(124)	283
Total other income (expense)	(1,581)	5,970	19,568	(1,015)	(884)	(1,218)	(1,281)	(1,436)	22,942	(4,819)	(3,622)
Income (loss) before income tax (provision) benefit	5,162	9,160	17,359	(12,795)	14,058	(2,484)	(2,901)	(12,537)	18,886	(3,864)	2,231
Income tax benefit (provision)	2,553	(3,365)	(8,010)	3,963	(5,329)	853	739	4,482	(4,859)	745	363
Net income (loss)	$ 7,715	$ 5,795	$ 9,349	$ (8,832)	$ 8,729	$ (1,631)	$ (2,162)	$ (8,055)	$ 14,027	$ (3,119)	$ 2,594
Net (loss) income per share - Basic (in dollars per share)	$ 0.20	$ 0.15	$ 0.24	$ (0.23)	$ 0.23	$ (0.04)	$ (0.06)	$ (0.21)	$ 0.36	$ (0.08)	$ 0.07
Net (loss) income per share - Diluted (in dollars per share)	$ 0.19	$ 0.15	$ 0.24	$ (0.23)	$ 0.22	$ (0.04)	$ (0.06)	$ (0.21)	$ 0.35	$ (0.08)	$ 0.07
Weighted average shares used in computing net (loss) income per share:
Basic (in shares)	38,873	38,714	38,574	38,278	38,097	37,999	37,860	37,484	38,611	37,862	36,856
Diluted (in shares)	39,809	39,536	39,340	38,278	39,040	37,999	37,860	37,484	39,625	37,862	38,257