Athenahealth (ATHN) 10-K 9 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 05, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	ATHN
Entity Registrant Name	Athenahealth Inc
Entity Central Index Key	1131096
Current Fiscal Year End Date	-19
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		38,195,739
Entity Public Float			$4,695,961,476

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$73,787	$65,002
Marketable securities	40,950	0
Accounts receivable, net	121,710	87,343
Restricted cash	0	3,000
Deferred tax assets, net	0	6,118
Prepaid expenses and other current assets	22,627	17,194
Total current assets	259,074	178,657
Property and equipment, net	271,552	213,018
Capitalized software costs, net	56,574	29,987
Purchased intangible assets, net	139,422	168,364
Goodwill	198,049	198,049
Investments and other assets	7,327	8,321
Total assets	931,998	796,396
Current liabilities:
Accounts payable	9,410	3,930
Accrued compensation	71,768	44,444
Accrued expenses	37,033	24,380
Line of credit	35,000	35,000
Long-term debt	15,000	15,000
Deferred revenue	28,949	27,002
Deferred tax liability, net	8,449	0
Total current liabilities	205,609	149,756
Deferred rent, net of current portion	19,412	1,478
Long-term debt, net of current portion	158,750	173,750
Deferred revenue, net of current portion	54,473	53,172
Long-term deferred tax liability, net	10,417	21,421
Other long-term liabilities	8,214	5,511
Total liabilities	456,875	405,088
Commitments and contingencies (Note 14)
Stockholders’ equity:
Preferred stock, $0.01 par value: 5,000 shares authorized; no shares issued and outstanding at December 31, 2014 and December 31, 2013, respectively	0	0
Common stock, $0.01 par value: 125,000 shares authorized; 39,402 shares issued and 38,124 shares outstanding at December 31, 2014; 38,600 shares issued and 37,322 shares outstanding at December 31, 2013	395	387
Additional paid-in capital	443,259	380,967
Treasury stock, at cost, 1,278 shares	-1,200	-1,200
Accumulated other comprehensive income (loss)	24,188	-446
Retained earnings	8,481	11,600
Total stockholders’ equity	475,123	391,308
Total liabilities and stockholders’ equity	$931,998	$796,396

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
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)	39,402,000	38,600,000
Common stock, shares outstanding (shares)	38,124,000	37,322,000
Treasury stock, shares (shares)	1,278,000	1,278,000

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Business services	$201,072	$179,711	$175,949	$154,502	$162,529	$141,326	$137,919	$121,463	$711,234	$563,237	$408,496
Implementation and other	12,142	10,717	9,973	8,533	9,050	10,201	8,382	4,133	41,365	31,766	13,775
Total revenue	213,214	190,428	185,922	163,035	171,579	151,527	146,301	125,596	752,599	595,003	422,271
Expense:
Direct operating	76,274	79,343	74,774	72,148	62,852	63,245	59,390	53,185	302,539	238,672	166,886
Selling and marketing	50,533	45,206	50,722	43,227	37,947	37,584	41,035	32,922	189,688	149,488	104,300
Research and development	19,802	18,087	16,417	15,155	16,322	15,104	14,269	11,944	69,461	57,639	33,792
General and administrative	33,592	31,800	30,443	29,357	22,339	21,690	24,670	31,077	125,192	99,776	57,025
Depreciation and amortization	18,071	17,258	15,186	14,249	12,864	11,263	11,107	8,341	64,764	43,575	25,641
Total expense	198,272	191,694	187,542	174,136	152,324	148,886	150,471	137,469	751,644	589,150	387,644
Operating (loss) income	14,942	-1,266	-1,620	-11,101	19,255	2,641	-4,170	-11,873	955	5,853	34,627
Other (expense) income:
Interest expense	-911	-1,244	-1,275	-1,265	-1,319	-1,421	-1,001	-164	-4,695	-3,905	-407
Other (expense) income	27	26	-6	-171	136	30	63	54	-124	283	658
Total other (expense) income	-884	-1,218	-1,281	-1,436	-1,183	-1,391	-938	-110	-4,819	-3,622	251
(Loss) income before income tax benefit (provision)	14,058	-2,484	-2,901	-12,537	18,072	1,250	-5,108	-11,983	-3,864	2,231	34,878
Income tax benefit (provision)	-5,329	853	739	4,482	-4,927	-80	-7,313	12,683	745	363	-16,146
Net (loss) income	$8,729	($1,631)	($2,162)	($8,055)	$13,145	$1,170	($12,421)	$700	($3,119)	$2,594	$18,732
Net (loss) income per share - Basic (in dollars per share)	$0.23	($0.04)	($0.06)	($0.21)	$0.35	$0.03	($0.34)	$0.02	($0.08)	$0.07	$0.52
Net (loss) income per share - Diluted (in dollars per share)	$0.22	($0.04)	($0.06)	($0.21)	$0.34	$0.03	($0.34)	$0.02	($0.08)	$0.07	$0.50
Weighted average shares used in computing net (loss) income per share:
Basic (in shares)	38,097	37,999	37,860	37,484	37,262	36,970	36,760	36,409	37,862	36,856	35,956
Diluted (in shares)	39,040	37,999	37,860	37,484	38,645	38,343	36,760	37,744	37,862	38,257	37,133

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net (loss) income	($3,119)	$2,594	$18,732
Other comprehensive income (loss)
Unrealized gain on securities, net of tax of $15,005, $5, and $3 for the years ended December 31, 2014, 2013, and 2012, respectively	24,845	13	32
Unrealized gain (loss) on change in fair value of interest rate swap, net of tax of ($9), $101, and $0 for the years ended December 31, 2014, 2013, and 2012, respectively	101	-253	0
Foreign currency translation adjustment	-312	-125	-12
Total other comprehensive income (loss)		-365	20
Comprehensive income	$21,515	$2,229	$18,752

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on securities, tax	$15,005	$5	$3
Unrealized loss on interest rate derivative, tax	($9)	$101	$0

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive (Loss) Income	Retained Earnings (Accumulated Deficit)	Total Stockholders' Equity
In Thousands, unless otherwise specified
Beginning Balance at Dec. 31, 2011		$367	$247,131	($1,200)	($101)	($9,726)	$236,471
Beginning Balance, in shares at Dec. 31, 2011		36,678		1,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation expense			28,082				28,082
Stock options exercised and restricted stock units vested, shares		849
Stock options and warrants exercised and restricted stock units vested, net		9	11,758				11,767
Common stock issued under employee stock purchase plan, shares		45
Common stock issued under employee stock purchase plan		0	2,426				2,426
Tax benefit realized from stock-based awards	14,100		14,150				14,150
Net (loss) income	18,732					18,732	18,732
Other comprehensive income	20				20		20
Ending Balance at Dec. 31, 2012		376	303,547	-1,200	-81	9,006	311,648
Ending Balance, in shares at Dec. 31, 2012		37,572		1,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation expense			44,842				44,842
Stock options exercised and restricted stock units vested, shares		983
Stock options and warrants 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		0	3,500				3,500
Tax benefit realized from stock-based awards	6,900		6,051				6,051
Net (loss) income	2,594					2,594	2,594
Other comprehensive income	-365				-365		-365
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
Ending Balance at Dec. 31, 2013	391,308	387	380,967	-1,200	-446	11,600	391,308
Ending Balance, in shares at Dec. 31, 2013		38,600		1,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation expense			60,258				60,258
Stock options exercised and restricted stock units vested, shares		758
Stock options and warrants 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		0	4,550				4,550
Tax benefit realized from stock-based awards	9,900		9,872				9,872
Net (loss) income	-3,119					-3,119	-3,119
Other comprehensive income					24,634		24,634
Ending Balance at Dec. 31, 2014	$475,123	$395	$443,259	($1,200)	$24,188	$8,481	$475,123
Ending Balance, in shares at Dec. 31, 2014		39,402		1,278

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net (loss) income	($3,119)	$2,594	$18,732
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	93,806	61,853	29,144
Excess tax benefit from stock-based awards	-10,060	-6,910	-14,179
Deferred income tax	-11,670	-7,044	-890
Change in fair value of contingent considerations	0	76	-5,118
Stock-based compensation expense	55,558	42,648	27,236
Other reconciling adjustments	-224	-67	1,092
Changes in operating assets and liabilities:
Accounts receivable, net	-34,367	-3,399	-12,611
Prepaid expenses and other current assets	4,285	3,283	12,096
Other long-term assets	596	-66	111
Accounts payable	2,546	-233	13
Accrued expenses and other long-term liabilities	10,083	-21	3,898
Accrued compensation	26,339	5,775	7,959
Deferred revenue	3,248	-3,090	2,969
Deferred rent	12,084	-2,091	-239
Net cash provided by operating activities	149,105	93,308	70,213
CASH FLOWS FROM INVESTING ACTIVITIES:
Capitalized software development costs	-53,477	-29,123	-15,657
Purchases of property and equipment	-76,092	-38,260	-23,904
Proceeds from sales and maturities of investments	0	56,245	160,340
Purchases of investments	0	-2,000	-118,919
Payments on acquisitions, net of cash acquired	0	-410,161	-5,798
Change in restricted cash	3,000	-1,643	3,650
Other investing activities	-750	0	172
Net cash used in investing activities	-127,319	-424,942	-116
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock under stock plans and warrants	21,041	31,133	18,699
Taxes paid related to net share settlement of stock awards	-28,879	-12,075	-4,248
Excess tax benefit from stock-based awards	10,060	6,910	14,179
Proceeds from long-term debt	0	200,000	0
Proceeds from line of credit	0	155,000	0
Payments for line of credit	0	-120,000	0
Payments for long-term debt	-15,000	-11,250	0
Net settlement of acquired company’s board of directors equity shares	0	-5,806	0
Debt issuance costs	0	-1,699	0
Payment of contingent consideration accrued at acquisition date	0	-525	-1,550
Net cash (used in) provided by financing activities	-12,778	241,688	27,080
Effects of exchange rate changes on cash and cash equivalents	-223	-40	30
Net (decrease) increase in cash and cash equivalents	8,785	-89,986	97,207
Cash and cash equivalents at beginning of period	65,002	154,988	57,781
Cash and cash equivalents at end of period	73,787	65,002	154,988
Non-cash transactions
Property, equipment and purchased software recorded in accounts payable and accrued expenses	12,036	1,667	4,217
Non-cash leasehold improvements	5,933	0	0
Taxes to be paid related to net share settlement of restricted stock units in accrued expenses	0	0	258
Grant from government program to be used to reduce non-income taxes recorded in investments and other assets and other long-term liabilities	90	936	0
Tax benefit recorded in prepaid expenses and other current assets	9,872	5,649	14,150
Fair value of equity awards assumed	0	13,028	0
Additional disclosures
Cash received for interest	0	451	1,960
Cash paid for interest	4,499	3,328	0
Cash (refunded) paid for taxes	($1,931)	$1,348	$3,932

NATURE_OF_OPERATIONS_AND_SUMMA

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2014
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”) is a business services company that provides ongoing billing, clinical-related, and other related services to its customers. Our services are delivered and consumed through a single instance of our cloud-based platform, athenaNet, through which we continuously update and 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 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 – 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 estimated 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) fair value of the reporting unit for goodwill impairment testing; and (8) litigation reserves. 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 making decisions regarding resource allocation and assessing performance. The Company, which uses consolidated financial information in determining how to allocate resources and assess performance, has determined that it operates in one segment and the CODM, our Chief Executive Officer, uses non-GAAP adjusted operating income (defined as GAAP net (loss) income before benefit from (provision for) 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 costs, transaction costs, and gain on early termination of lease) as the measure of our profit on a regular basis. During the year ended December 31, 2013, we acquired and integrated two significant businesses and re-evaluated our operating segments. As of December 31, 2014 and 2013, our CODM determined that the acquired businesses are so closely integrated, that 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 business services associated with our four integrated services and from subscriptions to and sponsored clinical information and decision support services for our point of care medical application. Our four integrated services consist of athenaCollector for revenue cycle and practice management, athenaClinicals for electronic health records (“EHR”) management, athenaCommunicator for patient communication management, and athenaCoordinator for care coordination and financial and quality management.
	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 our cloud-based network, athenaNet; minimum fees; flat fees; or per-claim fees, where applicable. We do not recognize revenue for 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.
	Subscriptions to the Epocrates point of care medical application are entered into by a member 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, and payment occurs at the time of order, which is in advance of the services being performed, and 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 both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in our control. Further, our revenue arrangements do not include a general right of return, as we deliver services and not products. We consider a deliverable to have standalone 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. We maintain a standard price list by service; however, certain incentives, such as discounts, may be offered to clients when they purchase multiple services. Such discounting is subject to various levels of management approval and any discount offered is based on the total contract value. 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 standalone sales of a deliverable have been priced within a reasonably narrow range in order to assert that we have established VSOE.
	When we cannot establish VSOE of fair value, we then determine if we can establish TPE of fair value. TPE is determined based on competitor prices for similar deliverables when sold separately. Our services differ significantly from that of our peers and our offerings contain a significant level of customization and differentiation such that the comparable pricing of products with similar functionality cannot be obtained. Furthermore, we are unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis. Therefore, we are typically unable to determine TPE.
	If both VSOE and TPE do not exist, we use BESP to establish fair value and to 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 revenue consists primarily of deferred professional services fees related to assisting customers with required implementation services, which include implementation, go-live and training support services. Historically, all of these fees are billed upfront and recorded as deferred revenue until the implementation was complete, and then, as the service does not have stand-alone value, it is 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. Previously deferred revenue balances related to implementation services that were billed up front and did not have stand alone value, will continue to be amortized over those remaining customer lives. Also, in 2014, 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.
	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 go-live and training of clients, and claim processing costs. We expense these 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 for research and development employees (including stock-based compensation) and consulting fees for third-party developers. All such costs are expensed as incurred, except for certain internal use software development costs, which may be capitalized. 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 share-based awards 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 grants 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 grant’s vesting determination date, which is the date our fiscal year financial statements are available. The grant 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 grants is recorded over the requisite service period, generally four years. Such options 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 $15.5 million, $14.2 million and $12.3 million for the years ended December 31, 2014, 2013, and 2012, 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.
	Restricted Cash – As of December 31, 2014 and 2013, restricted cash balances totaled $0.0 million and $3.0 million, respectively. The December 31, 2013 balance consists of escrowed funds held as a deposit associated with a possible pending lease. The amount was returned to us when the lease was signed in January 2014.
	Investments – Management determines the appropriate classification of investments at the time of purchase based upon management’s intent with regard to such investments. All investments, except for certain investments in privately-held companies which are accounted for at cost, are held as available-for-sale investments. Scheduled maturity dates of U.S. government-backed securities, corporate bonds and commercial paper purchased that are within one year are classified as short-term. Scheduled maturity dates of U.S. government-backed securities, corporate bonds and commercial paper that are in excess of one year are classified as long-term. All investments are recorded at fair value with unrealized holding gains and losses included in accumulated other comprehensive (loss) income. There were no material realized gains and losses on sales of these investments for the periods presented. The Company determines realized gains and losses based on the specific identification method.
	Financial Instruments – Certain financial instruments are required to be, and are recorded at fair value. The remaining financial instruments' carrying values approximate their fair value, primarily because of their short-term nature.
	Derivative financial instruments are used to manage certain of the Company’s interest rate exposures. The Company does not enter into derivatives for trading or speculative purposes. Derivatives are carried at fair value, as determined using standard valuation models, and adjusted when necessary for credit risk. Refer to Note 4 – Fair Value of Financial Instruments and Note 9 – Debt for additional information.
	Concentrations of Credit Risk – Financial instruments that potentially subject us to concentrations of credit risk are cash equivalents, investments, derivatives, and accounts receivable. We attempt to limit our credit risk associated with cash equivalents and investments by investing in highly-rated corporate and financial institutions, and engaging with highly-rated financial institutions as counterparties to its derivative transactions. With respect to customer accounts receivable, we manage our credit risk by performing ongoing credit evaluations of its customers. No single customer accounted for a significant amount of revenues for the years ended December 31, 2014, 2013, and 2012. No single customer accounted for a significant portion of accounts receivable as of December 31, 2014 and 2013.
	Accounts Receivable – Accounts receivable represents 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,
		2014			2013			2012
	Beginning balance	$	1,691		$	1,771		$	2,348
	Provision	(769		)	791			153
	Write-offs	(365		)	(871		)	(730		)
	Ending balance	$	557		$	1,691		$	1,771
	Property and Equipment – Property and equipment are stated at cost. Equipment, furniture, and fixtures are depreciated using the straight-line method over their estimated useful lives, generally ranging from three to five 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. Buildings are depreciated using the straight-line method over 30 to 40 years. Building improvements are depreciated using the straight-line method over 10 to 25 years. Aircraft and land improvements are depreciated using the straight-line method over 20 years and 10 years, respectively. Costs associated with maintenance and repairs are expensed as incurred.
	Capitalized Interest Cost – Interest costs related to major capital projects, specifically the Company’s corporate headquarters campus project and capitalized internal-use software development costs, are capitalized until the 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 costs related to athenaNet services and certain other projects for internal use incurred during the application development stage, including stock-based compensation expense for employees 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 three years. Amortization expense was $33.2 million, $18.0 million, and $9.0 million for the years ended December 31, 2014, 2013, and 2012, respectively. Future amortization expense for all software development costs capitalized as of December 31, 2014 is estimated to be $34.6 million, $17.4 million and $2.7 million for the years ending December 31, 2015, 2016, and 2017, respectively. In addition to the future amortization expenses, we have a $1.7 million balance in a capitalization in progress account related to software development 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, 2014, 2013, and 2012.
	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, used to measure the amount of impairment loss, 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, 2014, 2013, and 2012.
	Purchased Intangible Assets – Purchased intangible assets consist of technology, a physician network, content, a trade name, customer backlog, non-compete agreements and customer relationships 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,
		2014			2013
	Accrued bonus	$	38,938		$	25,013
	Accrued vacation	8,106			5,107
	Accrued payroll	19,846			8,611
	Accrued commissions	4,878			5,713
	Accrued compensation expenses	$	71,768		$	44,444
	Accrued expenses	$	31,162		$	23,775
	Accrued property and equipment additions	5,871			605
	Accrued expenses	$	37,033		$	24,380
	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 cash payments are recorded 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 is 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 estimated 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.
	Business Combinations – We apply business combination accounting when we have acquired control over one or more businesses. Business combinations are accounted for at fair value. The associated acquisition costs are generally expensed as incurred and recorded in general and administrative expenses; non-controlling interests are reflected at fair value at the acquisition date; in-process research and development is recorded at fair value as an intangible asset at the acquisition date; restructuring costs associated with a business combination are generally expensed rather than capitalized; 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 will 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, including contingent consideration, are based on management’s estimates and assumptions, as well as other information compiled by management, 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 transactions described in Note 2.
	Related Party Transaction – During the year ended December 31, 2013, we made a long-term investment in a vendor. The total expense related to this vendor for the years ended December 31, 2014 and 2013 was $11.3 million and $1.5 million, respectively, and the total amount payable related to this vendor at December 31, 2014 and 2013 was $1.3 million and $0.4 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.
	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 to reduce non-income taxes as a grant. Credits which are expected to be used to reduce non-income taxes are recognized when the requirements to earn the credits have been met.
	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 are 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.
	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.
	Recent Accounting Pronouncements – In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update (“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, the ASU 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). We are currently in the process of evaluating this new guidance. This guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. Early application is not permitted.

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS
	Watertown, MA Corporate Headquarters – Arsenal on the Charles
	On May 10, 2013, athenahealth, through its wholly-owned subsidiary Athena Arsenal, LLC, completed the acquisition of the Arsenal on the Charles, located in Watertown, Massachusetts. The Arsenal on the Charles is an expansive 29-acre, multi-building, commercial property where we were leasing space for our headquarters and related operating activities prior to the transaction. The purpose of this acquisition was to allow for future expansion of the corporate headquarters to accommodate anticipated headcount growth. The purchase price was $168.5 million, which was based on management’s estimates and assumptions based on the information that was available as of the date of the acquisition. The fair value of the consideration paid was $167.3 million, all of which was paid in cash.
	The following table summarizes the estimated fair values of assets acquired and liabilities assumed as of the date of acquisition:
	Prepaid expenses and other current assets	$	685
	Property, equipment and buildings	144,071
	Purchased intangible assets	25,545
	Accrued expenses	(271		)
	Deferred revenue	(789		)
	Other long-term liabilities	(1,916		)
	Total identifiable net assets	$	167,325
	The fair values assigned to tangible and identifiable intangible assets acquired and liabilities assumed were based on management’s estimates and assumptions and were based on the information that was available as of the date of the acquisition. Certain items, such as the working capital adjustments to the purchase price, were subject to change as additional information was received about facts and circumstances that existed at the date of acquisition. During the three months ended March 31, 2014, we finalized this valuation.
	The following table sets forth the fair value of the components of the identifiable intangible assets acquired by asset class:
	Above market leases		$	3,298
	In-place leases		22,247
	Total intangible assets subject to amortization		$	25,545
	The value of any in-place lease is estimated to be equal to the property owners’ avoidance of costs necessary to re-lease the property for a lease term equal to the remaining primary in-place lease term and the value of investment grade tenancy. The cost avoidance to the property owners of vacancy/leasing costs necessary to lease the property for a lease term equal to the remaining in-place lease term is derived first by determining the in-place lease term on the subject lease. Then, based on our review of the market, the cost to be borne by a property owner to replicate a market lease to the remaining in-place term was estimated. These costs consist of: (i) rent lost during downtime (e.g., assumed periods of vacancy), (ii) estimated expenses that would be incurred by the property owner during periods of vacancy, (iii) rent concessions (e.g., free rent), (iv) leasing commissions, and (v) tenant improvement allowances. We determined these values using our own estimates along with third-party appraisals. We amortize the capitalized value of in-place lease intangible assets to expense over the remaining initial term of each lease. We amortize the capitalized value of above market leases to expense over the initial and expected renewal terms of the leases. No amortization period for intangible assets will exceed the remaining depreciable life of the building.
	The amounts of third-party tenant revenue (included in the line item “Implementation and other”) and net (loss) from the Arsenal on the Charles included in our Consolidated Statements of Income from the acquisition date of May 10, 2013 through the periods ended December 31, 2013 and December 31, 2014 are as follows:
		Year ended December 31, 2014			May 10, 2013 through December 31, 2013
	Third-party tenant revenue	$	14,254		$	9,738
	Net (loss)	$	(8,739	)	$	(4,827	)
	Direct operating expense from the acquisition date of May 10, 2013, through the period ended December 31, 2013 and the twelve month period ended December 31, 2014, includes $9.1 million and $13.6 million of costs associated with third-party tenant revenue for the Arsenal on the Charles.
	We incurred transaction costs in connection with the acquisition of $2.4 million during the year ended December 31, 2013, and $3.1 million in total. These costs are included in general and administrative expenses.
	Epocrates, Inc.
	On March 12, 2013, we acquired Epocrates, a leading provider of essential clinical content, practice tools, and health industry engagement via mobile devices at the point of care. We acquired Epocrates for the assembled workforce, expected synergies, and accelerated awareness of athenahealth’s services across the physician market and to deliver high-value information to the clinical community. The acquisition date fair value of the consideration transferred for Epocrates, less cash and short-term investments acquired, was approximately $237.6 million, which consisted of the following:
	Cash payments	$	294,632
	Fair value of vested stock options and restricted stock units assumed	13,028
	Fair value of total consideration	307,660
	Less cash acquired	(51,796		)
	Less short-term investments acquired	(18,250		)
	Total	$	237,614
	The value of the share consideration for Epocrates’ common stock was based on the average closing sales prices per share of athenahealth common stock for the ten trading days ending on the second trading day prior to the closing of the acquisition. The fair value of the stock options and restricted stock units assumed by us was determined using the Black-Scholes option pricing model. The share conversion ratio of 0.1239 was applied to convert Epocrates stock options and restricted stock units to athenahealth stock options and restricted stock units.
	We assumed stock options and restricted stock units with a fair value of $22.6 million. Of the total consideration, $13.0 million was allocated to the purchase consideration and $9.6 million was allocated to future services and is being expensed on a straight-line basis over the remaining service periods. In the years ended December 31, 2014 and 2013, stock-based compensation expense recognized for stock options and restricted stock units assumed was $0.3 million and $7.4 million, respectively.
	The following table summarizes the preliminary and final fair values of assets acquired and liabilities assumed as of the date of acquisition, March 12, 2013, and upon completion of the valuation at December 31, 2013:
		12-Mar-13			Adjustments			31-Dec-13
	Accounts receivable	$	23,144		$	(1,116	)	$	22,028
	Other current and long-term assets	3,833			650			4,483
	Property, equipment and capitalized software costs	4,168			20			4,188
	Purchased intangible assets	139,900			(500		)	139,400
	Current liabilities	(11,054		)	(282		)	(11,336		)
	Deferred tax liabilities, net	(39,811		)	(1,340		)	(41,151		)
	Deferred revenue	(29,400		)	648			(28,752		)
	Other long-term liabilities	(1,259		)	53			(1,206		)
	Total identifiable net assets	89,521			(1,867		)	87,654
	Goodwill	148,093			1,867			149,960
		$	237,614		$	—		$	237,614
	The excess of purchase consideration over the fair value of net tangible and identifiable intangible assets acquired was recorded as goodwill. The fair values assigned to tangible and identifiable intangible assets acquired and liabilities assumed were based on management’s estimates and assumptions based on the information that was available as of the date of the acquisition. The fair values of certain items, such as accounts receivable, purchased intangible assets, current and non-current income taxes payable, deferred taxes, deferred revenue and uncertain tax benefits, were subject to change as additional information was received about facts and circumstances that existed at the date of acquisition and as certain tax returns were finalized. The fair values were finalized during the quarter ended December 31, 2013.
	The following table sets forth the components of the identifiable intangible assets acquired by asset class and their estimated useful lives as of the date the fair values were finalized:
		Fair Value			Useful Life
	Physician network	104,000			14 years
	Drug information content	10,000			5 years
	Trade name	11,500			10 years
	Customer backlog	2,900			1.5 years
	Developed technology	6,500			3 years
	Epocrates non-compete agreement	4,500			1.5 years
	Total intangible assets subject to amortization	$	139,400
	The physician network represents the fair values of the underlying relationships and agreements with Epocrates customers and the fair values of the savings associated with future marketing spend for the athenahealth services to the acquired physician network. Drug information content represents the fair value of the cost to replace the drug information and interactive content used by the physician network. The trade name represents the fair value of the brand and name recognition associated with the marketing of Epocrates’ service offerings. Customer backlog represents the estimated fair value of existing contractual backlog orders as of the acquisition date. Developed technology represents the estimated fair value of Epocrates’ mobile device platform. Epocrates non-compete agreement represents the estimated fair value of the contract between athenahealth and a former member of Epocrates management. All of the purchased intangible assets related to the Epocrates transaction have finite lives. For those purchased intangible assets where an income approach was used, we considered the projected undiscounted cash flows as the best indication of the pattern of economic benefit expected from each asset.
	The goodwill balance is primarily attributed to the assembled workforce and expanded market opportunities when integrating Epocrates’ mobile device platform with the athenahealth service offerings. The goodwill balance is not deductible for U.S. income tax purposes.
	The amounts of revenue and net income (loss) of Epocrates included in our Consolidated Statements of Income from the acquisition date of March 12, 2013 through the period ended December 31, 2013 and for the period ended December 31, 2014 are as follows:
		Year ended December 31, 2014			March 12, 2013 through December 31, 2013
	Revenue	$	44,442		$	52,380
	Net income (loss)	(a)			$	(14,447	)
	(a) As we have fully integrated our operations, it is impracticable for us to disclose the net income (loss) associated with the acquired business for the year ended December 31, 2014
	The net loss for the period ended December 31, 2013 includes $7.9 million in stock-based compensation expense primarily related to the acceleration of certain individuals’ stock awards upon termination.
We incurred transaction costs in connection with the acquisition of $2.7 million during the year ended December 31, 2013, and $3.2 million in total. These costs are included in general and administrative expenses.
As part of the integration of Epocrates, we communicated to certain employees severance and retention bonuses which were expensed during 2013. If the employee did not fulfill the required employment period for the retention bonus, the amount was not paid and the expense was reversed. The following table summarizes these amounts on the Consolidated Statements of Income for the years ended December 31, 2013 and 2014:
Rollforward of integration costs
Beginning balance, January 1, 2013	$	—
Addition to provision	3,909
Cash payments	(3,574		)
Ending balance, December 31, 2013	$	335
Reversal to provision	(42		)
Cash payments	(293		)
Ending balance, December 31, 2014	$	—
Pro Forma Presentation
The following pro forma financial information summarizes the combined results of operations for athenahealth as though the acquisitions of Epocrates and the Arsenal on the Charles occurred on January 1, 2012. The unaudited pro forma financial information is as follows:
	Year Ended December 31,
	2013			2012
Revenue	$	614,775		$	538,030
Net loss	$	(1,808	)	$	(4,700	)
Net loss per share – Basic	$	(0.05	)	$	(0.13	)
Net loss per share – Diluted	$	(0.05	)	$	(0.13	)
The pro forma financial information for all periods presented has been calculated after adjusting the results of Epocrates and the Arsenal on the Charles to reflect the business combination accounting effects resulting from these acquisitions including the amortization expenses from acquired intangible assets, the depreciation expenses from acquired tangible assets, the stock-based compensation expense for unvested stock options and restricted stock units assumed, and the related tax effects as though the acquisition occurred as of January 1, 2012. The pro forma financial information is for informational purposes only and is not indicative of the results of operations that would have been achieved if the acquisition had taken place at the beginning of our 2012 fiscal year.

NET_LOSS_INCOME_PER_SHARE

NET (LOSS) INCOME PER SHARE	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
NET (LOSS) INCOME PER SHARE	NET (LOSS) INCOME PER SHARE
	Basic net (loss) income per share is computed by dividing net (loss) income by the weighted average number of common shares outstanding during the period. Diluted net (loss) income per share is computed by dividing net (loss) income 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 (loss) income per share if their effect would be anti-dilutive to earnings per share.
	The following table reconciles the weighted average shares outstanding for basic and diluted net (loss) income per share for the periods indicated:
		Years Ended December 31,
		2014			2013		2012
	Net (loss) income	$	(3,119	)	$	2,594	$	18,732
	Weighted average shares used in computing basic net (loss) income per share	37,862			36,856		35,956
	Net (loss) income per share – basic	$	(0.08	)	$	0.07	$	0.52
	Net (loss) income	$	(3,119	)	$	2,594	$	18,732
	Weighted average shares used in computing basic net (loss) income per share	37,862			36,856		35,956
	Effect of dilutive securities	—			1,401		1,177
	Weighted average shares used in computing diluted net (loss) income per share	37,862			38,257		37,133
	Net (loss) income per share – diluted	$	(0.08	)	$	0.07	$	0.5
	The computation of diluted net income per share does not include 0.4 million and 0.4 million of stock options and restricted stock units for the years ended December 31, 2013 and December 31, 2012, respectively, because their inclusion would have an anti-dilutive effect on net income per share.

FAIR_VALUE_OF_FINANCIAL_INSTRU

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS
	As of December 31, 2014 and 2013, the carrying amounts of cash and cash equivalents, restricted cash, receivables, accounts payable, and accrued expenses approximated their estimated fair values because of the short-term nature of these financial instruments. 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 (see Note 9 – Debt); as of December 31, 2013, we had $188.8 million outstanding on our term loan facility and $35.0 million outstanding on our revolving credit facility. These carrying amounts approximate fair values due to their variable rate nature at current market rates.
	During 2014, we launched our MDP Accelerator portfolio, a program designed to cultivate heath care information technology start-ups and expand services offered to our physician network. Our investment totals $0.8 million short-term convertible note receivable, and is included in prepaid expenses and other current assets on our Consolidated Balance Sheets. At December 31, 2014, as there is no indication of performance risk and no conversion is currently contemplated, we estimate that the fair value of this note receivable approximates cost, based on inputs including the original transaction price, our own recent transactions in the same or similar instruments, completed or pending third-party transactions in the underlying investment, 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. 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 periods presented.
	We previously invested a total of $1.1 million in Castlight Health, Inc. (“Castlight”), a leading provider of cloud-based software that enables enterprises to control health care costs. This investment was initially recorded and subsequently carried at cost through December 31, 2013. On March 14, 2014, an initial public offering (“IPO”) of shares of Castlight’s Class B common stock was made available for sale on the New York Stock Exchange under the symbol “CSLT.” As a result of the IPO, we classified this investment as “available-for-sale” and marked-to-market the shares we hold based on quoted market prices. As of December 31, 2014, the aggregate fair value of the investment was $41.0 million and is recorded in the Marketable securities line on the Consolidated Balance Sheet. The unrealized gain on investment of $39.9 million for the year ended December 31, 2014 is included in other comprehensive (loss) income, net of a $15.0 million short-term deferred tax liability.
	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, if any, associated with the interest rate swap will be reported in interest expense. For the years ended December 31, 2014 and 2013, 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, 2014 and 2013, nor was any amount excluded from ineffectiveness testing. We do not expect that any of the approximately $0.2 million of pre-tax unrealized losses included in accumulated other comprehensive income (loss) at December 31, 2014 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, 2014 and 2013 was a liability of $0.2 million and $0.4 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, 2014 and December 31, 2013, 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.
			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 (a)		$	—	$	(244	)	$	—	$	(244	)
	Total liabilities		$	—	$	(244	)	$	—	$	(244	)
			Fair Value Measurements as of December 31, 2013, Using
			Level 1		Level 2			Level 3		Total
	Cash and cash equivalents:
	Money market funds		$	26	$	—		$	—	$	26
	Total assets		$	26	$	—		$	—	$	26
	Interest rate swap liability (a)		$	—	$	(354	)	$	—	$	(354	)
	Total liabilities		$	—	$	(354	)	$	—	$	(354	)
	(a)	Recorded in other long-term liabilities on the Consolidated Balance Sheets.
	The following table presents the Company's financial instruments measured at fair value using unobservable inputs (Level 3) as of each of the years ended December 31, 2014 and 2013:
			Fair Value Measurements Using Unobservable Inputs (Level 3)
			Year Ended December 31, 2014		Year Ended December 31, 2013
	Balance beginning of period		$	—	$	448
	Payments		—		(524		)
	Additions		750		—
	Change in fair value (included in G&A expenses)		—		76
	Balance end of period		$	750	$	—

INVESTMENTS

INVESTMENTS	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
INVESTMENTS	INVESTMENTS
	We had the following available-for-sale securities as of December 31, 2014:
		Cost		Gross		Fair Value
				Unrealized Gain
	Marketable equity securities	$	1,100	$	39,850	$	40,950
	As of December 31, 2013, we had no available-for-sale securities.

PROPERTY_AND_EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT
	The Company has no capital leases for the years ended December 31, 2014 and December 31, 2013.
	The fair values of the property and equipment acquired as part of the purchase of the Arsenal on the Charles are allocated to buildings, land, and land improvements in the amounts of $121.3 million, $21.0 million, and $1.8 million, respectively.
	Property and equipment consist of the following:
		Years Ended December 31,
		2014			2013
	Equipment	$	93,583		$	78,616
	Furniture and fixtures	14,760			8,822
	Leasehold improvements	18,113			3,104
	Aircraft	15,054			3,156
	Building	131,746			136,368
	Building improvements	49,671			24,441
	Land	23,059			23,059
	Land improvements	4,339			2,980
	Total property and equipment, at cost	350,325			280,546
	Accumulated depreciation and amortization	(96,416		)	(72,777		)
	Construction in progress	17,643			5,249
	Property and equipment, net	$	271,552		$	213,018
	Depreciation expense on property and equipment was $31.5 million, $25.5 million, and $16.6 million for the years ended December 31, 2014, 2013, and 2012, respectively.

GOODWILL_AND_PURCHASED_INTANGI

GOODWILL AND PURCHASED INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2014
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, 2014 and 2013:
	Gross balance as of January 1, 2013	$	48,090
	Goodwill recorded in connection with the acquisition of Epocrates, Inc.	149,959
	Gross balance as of December 31, 2013	$	198,049
	Gross balance as of December 31, 2014	$	198,049
	Purchased Intangible Assets
	Definite-lived intangible assets acquired as of December 31, 2014 and 2013 are as follows:
			December 31, 2014
			Gross		Accumulated			Net		Weighted Average Remaining
					Amortization					Useful Life (years)
	Developed technology		$	9,721	$	(6,294	)	$	3,427	1.1
	Customer relationships		21,434		(9,555		)	11,879		5.7
	Doctor network		104,000		(9,792		)	94,208		12.2
	Drug information content		10,000		(3,608		)	6,392		3.2
	Trade name		11,500		(2,074		)	9,426		8.2
	Non-compete agreement		1,178		(873		)	305		0.8
	Above market leases		3,016		(916		)	2,100		1.6
	Leases in place		19,695		(8,065		)	11,630		3.9
	Total		$	180,544	$	(41,177	)	$	139,367
			December 31, 2013
			Gross		Accumulated			Net		Weighted Average Remaining
					Amortization					Useful Life (years)
	Developed technology		$	11,721	$	(4,737	)	$	6,984	2
	Customer relationships		21,434		(7,365		)	14,069		6.6
	Doctor network		104,000		(682		)	103,318		13.2
	Drug information content		10,000		(1,608		)	8,392		4.2
	Trade name		11,500		(924		)	10,576		9.2
	Customer backlog		2,900		(1,554		)	1,346		0.7
	Non-compete agreement		6,178		(3,280		)	2,898		1
	Above market leases		3,123		(357		)	2,766		5.9
	Leases in place		21,578		(3,563		)	18,015		5.3
	Total		$	192,434	$	(24,070	)	$	168,364
	Amortization expense for the years ended December 31, 2014, 2013, and 2012 was $28.6 million, $17.9 million, and $3.4 million, respectively, and is included in direct operating expenses. Estimated amortization expense, based upon our intangible assets at December 31, 2014, is as follows:
	Year ending December 31,	Amount
	2015	$	20,272
	2016	16,240
	2017	15,743
	2018	14,324
	2019	13,941
	Thereafter	58,847
	Total	$	139,367
	During the year ended December 31, 2014 we purchased indefinite-lived licenses of $0.1 million related to the development of our campus.

OPERATING_LEASES_AND_OTHER_COM

OPERATING LEASES AND OTHER COMMITMENTS	12 Months Ended
	Dec. 31, 2014
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 2015 to 2029.
	We entered into a lease agreement with a landlord in connection with the relocation of our corporate offices in June 2005 to the Arsenal on the Charles. Under the terms of such lease agreement, the landlord provided approximately $11.5 million in allowances to us for the leasehold improvements for the office space, reimbursement of moving costs and all payments under our lease agreement relating to our previous office space. Prior to May 2011, the incentive payments received from the new landlord were being recognized over the lease term and accounted for as a component of deferred rent on our Consolidated Balance Sheets. In May 2011, we paid $2.1 million to settle the remaining amounts of these rental incentive loans. In May 2013, this lease was effectively terminated when we purchased the Arsenal on the Charles from the landlord (see Note 2). During 2013, we recognized a $2.5 million net gain due to the early termination of our lease and the realization of the remaining balance in deferred rent at the time of acquisition. This gain was recorded in general and administrative expense.
	During the year ended December 31, 2014 we expanded in four of our locations which are under operating lease. Rent expense totaled $9.9 million, $5.5 million, and $4.9 million for the years ended December 31, 2014, 2013, and 2012, respectively.
	Future minimum lease payments under non-cancelable operating leases as of December 31, 2014 are as follows:
	Year ending December 31,	Future Rent
		Payments
	2015	$	7,994
	2016	12,878
	2017	12,457
	2018	12,238
	2019	11,789
	Thereafter	88,008
	Total minimum lease payments	$	145,364

DEBT

DEBT	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
DEBT	DEBT
	2011 Line of Credit – On October 20, 2011, we entered into a five-year, $100.0 million revolving credit facility (“Revolving Credit Facility”). The Revolving Credit Facility contained certain covenants, including consolidated leverage and minimum fixed charge coverage ratios. The interest rates applicable to revolving loans under the Revolving Credit Facility were at either (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’s 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.
	In connection with the planned acquisition of Epocrates, on January 3, 2013, we borrowed $100.0 million from the Revolving Credit Facility and, on January 9, 2013, repaid the borrowed amount in full.
	2013 Commitment Letter – On January 7, 2013, we entered into a commitment letter, pursuant to which Bank of America, N.A. committed to increase its commitment to provide revolving loans under the Revolving Credit Facility by an amount up to $55.0 million as a source of funding for the Epocrates transaction (see Note 2 – Acquisitions). We were required to pay financing fees of $0.3 million for this commitment. On March 11, 2013, we borrowed $155.0 million under the Revolving Credit Facility as a source of funding for the Epocrates transaction. All amounts outstanding under the Revolving Credit Facility were repaid by May 10, 2013.
	2013 Credit Agreement – 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”). The Senior Credit Facility replaced the Revolving Credit Facility. The Senior Credit Facility contains terms and conditions that are customary to facilities of this nature and certain covenants, including consolidated leverage ratio and capital expenditures limitations. The Senior Credit Facility may be used to refinance existing indebtedness, to finance the acquisition of the Arsenal on the Charles, and for working capital and other general corporate purposes. We may increase the Senior Credit Facility up to an additional $100.0 million, subject to certain terms, including obtaining lender commitments. The Senior Credit Facility expires on May 10, 2018, although we may prepay the 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 athenahealth in whole or in part without penalty or premium.
	On May 10, 2013, we borrowed $200.0 million under the unsecured term loan facility and $50.0 million under the unsecured revolving credit facility of the Senior Credit Facility to refinance existing indebtedness described above, to finance the Arsenal on the Charles acquisition as described in Note 2 – Acquisitions, and for working capital and other general corporate purposes. The unsecured term loan facility was payable quarterly starting in June 30, 2013, in the amount of $3.8 million each quarter. 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. As of December 31, 2014, there was $90.0 million available on the unsecured revolving credit facility.
	Any loan under the Senior Credit Facility bears interest at the same rates as in the Revolving Credit Facility. The interest rate for the Senior Credit Facility as of December 31, 2014 was 1.16%.
	The Company was required to pay financing fees of $1.4 million for the Senior Credit Facility, which are being amortized as interest expense in the Consolidated Statements of Income over the five-year term of the agreement.
	Future principal payments of the unsecured term loan facility at December 31, 2014 are as follows:
		Amount
	2015	$	15,000
	2016	15,000
	2017	15,000
	2018	128,750
	Total	$	173,750
	Less current portion	15,000
	Long-term portion	$	158,750
	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 outstanding borrowings under the Senior Credit Facility at 0.8396% exclusive of the credit spread under the Senior Credit Facility.
	The fair value of the interest rate swap recognized in other long-term liabilities and in OCI was as follows:
							Fair Value
	Effective Date	Notional Amount		Fixed Rate		Maturity	December 31, 2014			December 31, 2013
	August 31, 2013	120,000		0.8396	%	August 31, 2016	$	(244	)	$	(354	)
	Refer to Note 4 – Fair Value of Financial Instruments for further information.

STOCKHOLDERS_EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY
	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, 2014 and 2013, 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.

STOCKBASED_COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2014
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, 2014, 2013, and 2012 is as follows:
		Year Ended December 31,
		2014				2013			2012
	Stock-based compensation charged to:
	Direct operating	$	12,009			$	7,778		$	5,619
	Selling and marketing	14,581				12,057			7,717
	Research and development	7,221				4,238			3,213
	General and administrative	21,747				18,575			10,687
	Total	$	55,558			$	42,648		$	27,236
	Amortization of capitalized stock-based compensation related to software development	2,258				1,027			257
	Total	$	57,816			$	43,675		$	27,493
	In addition, for the years ended December 31, 2014 and 2013, $4.7 million and $2.2 million of stock-based compensation was capitalized in the line item "Capitalized software costs, net" in the Consolidated Balance Sheets for which $2.3 million and $1.0 million 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. As part of the Epocrates acquisition, we assumed 0.4 million shares available for issuance under the Epocrates stock plan. As of December 31, 2014 and 2013, there were approximately 4,023 and 4,609 shares, respectively, available for grant under our stock award plans.
	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, with the exception of options granted to members of the Board of Directors, which vest on a quarterly basis.
	The following table presents the stock option activity for the year ended December 31, 2014:
		Shares			Weighted-			Weighted-		Aggregate
					Average			Average		Intrinsic
					Exercise			Remaining		Value
					Price			Contractual Term
								(in years)
	Outstanding – January 1, 2014	2,167			$	48.69
	Granted	188			183.36
	Exercised	(470	)		35.08
	Forfeited	(35	)		87.24
	Outstanding – as of December 31, 2014	1,850			65.14			6		$	156,804
	Exercisable – as of December 31, 2014	1,235			$	43.5		5		$	126,318
	Vested and expected to vest as of December 31, 2014	1,754			$	61.87		5.9		$	153,142
	Weighted-average fair value of options granted for the year ended December 31, 2014				$	77.55
	We assumed stock options related to the acquisition of Epocrates based on a conversion ratio of 0.1239. We recorded compensation expense in relation to stock options of $11.7 million, $14.0 million, and $9.8 million, for the years ended December 31, 2014, 2013, and 2012, respectively.
	The following table illustrates the range of assumptions used to compute stock-based compensation expense for awards granted:
		Year Ended December 31,
		2014		2013		2012
	Risk-free interest rate	.66% - 1.67%		.35% - .75%		1.00%
	Expected dividend yield	—%		—%		—%
	Expected option term (years)	3.0 - 5.0		3.0 - 5.0		3.0 - 5.0
	Expected stock volatility	46% - 47%		41% - 45%		43% - 52%
	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, 2014 and 2013, there was $16.5 million and $17.4 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 2.5 years. The weighted average fair value of stock options granted during the years ended December 31, 2014, 2013, and 2012 was $77.55, $38.09, and $31.71, respectively. The intrinsic value of options exercised during the years ended December 31, 2014, 2013, and 2012 was $53.5 million, $53.2 million, and $36.1 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 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, 2014:
		Shares			Weighted-
					Average
					Grant
					Date
					Fair Value
	Outstanding – January 1, 2014	1,193			$	75.2
	Granted	556			181.81
	Vested	(452	)		67.39
	Forfeited	(87	)		109.94
	Outstanding – as of December 31, 2014	1,210			$	124.65
	We assumed restricted stock units related to the acquisition of Epocrates based on a conversion ratio of 0.1239. As of December 31, 2014, $111.0 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 $42.2 million, $27.4 million, and $17.3 million was recorded for restricted stock units during the years ended December 31, 2014, 2013, and 2012, respectively. The weighted average fair value of restricted stock units granted during the years ended December 31, 2014, 2013, and 2012 was $181.81, $98.34, and $71.15, respectively. The intrinsic value of vested restricted stock units during the years ended December 31, 2014, 2013, and 2012 was $78.5 million, $35.2 million, and $15.1 million, respectively.
	Employee Stock Purchase Plan
	Our 2007 Employee Stock Purchase Plan (“2007 ESPP”) 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, 2014, 2013, and 2012 was $1.7 million, $1.2 million, and $1.0 million, respectively.

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES
	The components of our income tax benefit (provision) for the years ended December 31, 2014, 2013, and 2012 are as follows:
		2014				2013				2012
	Current Benefit (Provision):
	Federal	$	(9,656	)		$	(4,225	)		$	(13,089	)
	State	(884		)		(1,495		)		(3,575		)
	Foreign	(385		)		(961		)		(372		)
		(10,925		)		(6,681		)		(17,036		)
	Deferred Benefit (Provision):
	Federal	10,695				5,291				(26		)
	State	906				1,753				802
	Foreign	69				—				114
		11,670				7,044				890
	Total income tax benefit (provision)	$	745			$	363			$	(16,146	)
	The components of the Company’s deferred income taxes as of December 31, 2014 and 2013 are as follows:
		2014				2013
	Deferred tax assets:
	Federal net operating loss carryforward	$	—			$	187
	State net operating loss carryforward	1,694				1,476
	Research and development tax credits	3,328				3,244
	Allowances for accounts receivable	1,168				2,773
	Deferred rent obligation	7,555				328
	Stock compensation	25,264				18,270
	Other accrued liabilities	2,223				2,171
	Deferred revenue	17,797				17,754
	Other	1,473				3,101
	Total gross deferred tax assets	60,502				49,304
	Valuation allowance	(3,420		)		(2,627		)
	Total deferred tax assets	57,082				46,677
	Deferred tax liabilities:
	Intangible assets	(40,463		)		(49,555		)
	Capitalized software development	(15,769		)		(8,641		)
	Property and equipment	(4,621		)		(3,784		)
	Investments	(14,913		)		—
	Total deferred tax liabilities	(75,766		)		(61,980		)
	Net deferred tax (liabilities) assets	$	(18,684	)		$	(15,303	)
	We classify our deferred tax assets and liabilities as current or non-current based on the classification of the related asset or liability for financial reporting giving rise to the temporary difference. A deferred tax asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to net operating loss (“NOL”) carryforwards, is classified according to the expected reversal date. We recorded a valuation allowance against certain deferred tax assets related to state NOL carryforwards, foreign tax credits and research and development tax credits. We evaluated the ability to utilize the losses and credits and determined they could not meet the more likely than not standard.
	During the year ended December 31, 2014, we utilized tax attributes to reduce the current tax provision by $9.9 million respectively. During the year ended December 31, 2013, we utilized tax attributes to reduce the current tax provision by $7.0 million. During the year ended December 31, 2012, we utilized tax attributes to reduce the current tax provision by $2.8 million.
	As of December 31, 2014, we had federal and state NOL carryforwards of approximately $73.6 million (which include $73.6 million of NOL carryforwards from stock-based compensation) and $67.7 million (which include $32.7 million of NOL carryforwards from stock-based compensation), respectively, to offset future federal and state taxable income. The state NOL carryforwards begin to expire in 2018, and the federal NOL carryforwards expire at various times from 2020 through 2034. As of December 31, 2013, we had federal and state NOL carryforwards of approximately $28.0 million (which include $27.5 million of NOL carryforwards from stock-based compensation) and $26.0 million (which include $1.6 million of NOL carryforwards from stock-based compensation), respectively, to offset future federal and state taxable income.
	We have 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, 2014, 2013, and 2012, we realized excess tax benefits from federal and state tax deductions of $9.9 million, $6.9 million and $14.1 million, respectively, which were credited to additional paid-in capital. As of December 31, 2014, the amount of unrecognized federal and state excess tax benefits is $35.4 million and $3.7 million, respectively, which will be credited to additional paid-in capital when realized.
	Our research and development tax credits carryforward is available to offset future federal and state taxes, and the credits expire at various times through 2034. We have federal and state R&D credits of $9.6 million (which include $9.6 million from the utilization of credits under the without method of accounting related to stock-based compensation) and $3.9 million (which include $1.8 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, 2014, 2013, and 2012:
		2014			2013			2012
	Income tax computed at federal statutory tax rate	35	%		35	%		35	%
	State taxes, net of federal benefit	6	%		(6	)%		5	%
	Research and development credits	86	%		(98	)%		—	%
	Permanent differences	(87	)%		20	%		6	%
	Valuation allowance	(21	)%		33	%		—	%
	Total	19	%		(16	)%		46	%
	A reconciliation of the beginning and ending amount of uncertain tax benefits is as follows:
		2014				2013				2012
	Beginning uncertain tax benefits	$	4,851			$	1,761			$	1,685
	Prior year – decreases	(79		)		(537		)		(140		)
	Prior year – increases	887				501				177
	Acquired balances	—				2,339				—
	Current year - decreases	(212		)		—				—
	Current year – increases	366				787				39
	Ending uncertain tax benefits	$	5,813			$	4,851			$	1,761
	Included in the balance of unrecognized tax benefits at December 31, 2014 are $5.1 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.
	Interest and penalties included in the tax benefit (provision) amounted to $0.8 million and $0.5 million for the years ended December 31, 2014 and 2013, respectively. Accrued interest and penalties amounted to $1.2 million and $0.7 million as of December 31, 2014 and 2013, respectively. The accrued interest and penalties balances were adjusted for foreign currency gains during the year ended December 31, 2014 and 2013 of $0.3 million and $0.1 million, respectively.
	We are subject to taxation in the United States, various states and India. As of December 31, 2014, tax years 1997 through 2013 – except for 2006 through 2008 for federal purposes – remain open to examination by major taxing jurisdictions to which we are subject, which years primarily resulted in carryforward attributes that 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.

EMPLOYEE_BENEFIT_PLAN

EMPLOYEE BENEFIT PLAN	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
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. During the years ended December 31, 2014, 2013, and 2012, our contributions to the 401(k) Plan were $4.5 million, $3.2 million, and $2.4 million, respectively.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2014
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 dispositions 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_INFORMATIO

QUARTERLY FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL INFORMATION	QUARTERLY FINANCIAL INFORMATION (UNAUDITED)
	Selected quarterly financial information follows for the year ended December 31, 2014:
		First			Second			Third			Fourth			Year
		Quarter			Quarter			Quarter			Quarter
	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
	Selected quarterly financial information follows for the year ended December 31, 2013:
		First			Second			Third			Fourth			Year
		Quarter			Quarter			Quarter			Quarter
	Revenue:
	Business services	$	121,463		$	137,919		$	141,326		$	162,529		$	563,237
	Implementation and other	4,133			8,382			10,201			9,050			31,766
	Total revenue	125,596			146,301			151,527			171,579			595,003
	Expense:
	Direct operating	53,185			59,390			63,245			62,852			238,672
	Selling and marketing	32,922			41,035			37,584			37,947			149,488
	Research and development	11,944			14,269			15,104			16,322			57,639
	General and administrative	31,077			24,670			21,690			22,339			99,776
	Depreciation and amortization	8,341			11,107			11,263			12,864			43,575
	Total expense	137,469			150,471			148,886			152,324			589,150
	Operating (loss) income	(11,873		)	(4,170		)	2,641			19,255			5,853
	Other (expense) income:
	Interest expense	(164		)	(1,001		)	(1,421		)	(1,319		)	(3,905		)
	Other (expense) income	54			63			30			136			283
	Total other expense	(110		)	(938		)	(1,391		)	(1,183		)	(3,622		)
	(Loss) income before income tax benefit (provision)	(11,983		)	(5,108		)	1,250			18,072			2,231
	Income tax benefit (provision)	12,683			(7,313		)	(80		)	(4,927		)	363
	Net income (loss)	$	700		$	(12,421	)	$	1,170		$	13,145		$	2,594
	Net income (loss) per share – Basic	$	0.02		$	(0.34	)	$	0.03		$	0.35		$	0.07
	Net income (loss) per share – Diluted	$	0.02		$	(0.34	)	$	0.03		$	0.34		$	0.07
	Weighted average shares used in computing net income (loss) per share:
	Basic	36,409			36,760			36,970			37,262			36,856
	Diluted	37,744			36,760			38,343			38,645			38,257
	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.

SUBSEQUENT_EVENT

SUBSEQUENT EVENT	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT
	On January 13, 2015, we acquired Razor Insights, LLC, who provides cloud-based billing and electronic health record software services to rural and community hospitals, for $40 million in cash. We acquired RazorInsights for the assembled workforce, technology, customer base and to accelerate our entrance into serving the inpatient segment.
	On January 23, 2015, we signed an agreement to purchase a suite of internally-developed clinical applications and an electronic health record system from Beth Israel Deaconess Medical Center, Inc. referred to as webOMR for $22 million in cash. The agreement also provides for up to an additional $18 million in contingent payments upon certain milestones in the future.

NATURE_OF_OPERATIONS_AND_SUMMA1

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General – athenahealth, Inc. (the “Company,” “we,” “us,” or “our”) is a business services company that provides ongoing billing, clinical-related, and other related services to its customers. Our services are delivered and consumed through a single instance of our cloud-based platform, athenaNet, through which we continuously update and 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 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 estimated 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) fair value of the reporting unit for goodwill impairment testing; and (8) litigation reserves. Actual results could significantly differ from those estimates.
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 business services associated with our four integrated services and from subscriptions to and sponsored clinical information and decision support services for our point of care medical application. Our four integrated services consist of athenaCollector for revenue cycle and practice management, athenaClinicals for electronic health records (“EHR”) management, athenaCommunicator for patient communication management, and athenaCoordinator for care coordination and financial and quality management.
	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 our cloud-based network, athenaNet; minimum fees; flat fees; or per-claim fees, where applicable. We do not recognize revenue for 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.
	Subscriptions to the Epocrates point of care medical application are entered into by a member 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, and payment occurs at the time of order, which is in advance of the services being performed, and 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 both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in our control. Further, our revenue arrangements do not include a general right of return, as we deliver services and not products. We consider a deliverable to have standalone 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. We maintain a standard price list by service; however, certain incentives, such as discounts, may be offered to clients when they purchase multiple services. Such discounting is subject to various levels of management approval and any discount offered is based on the total contract value. 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 standalone sales of a deliverable have been priced within a reasonably narrow range in order to assert that we have established VSOE.
	When we cannot establish VSOE of fair value, we then determine if we can establish TPE of fair value. TPE is determined based on competitor prices for similar deliverables when sold separately. Our services differ significantly from that of our peers and our offerings contain a significant level of customization and differentiation such that the comparable pricing of products with similar functionality cannot be obtained. Furthermore, we are unable to reliably determine what similar competitor products’ selling prices are on a stand-alone basis. Therefore, we are typically unable to determine TPE.
	If both VSOE and TPE do not exist, we use BESP to establish fair value and to 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 revenue consists primarily of deferred professional services fees related to assisting customers with required implementation services, which include implementation, go-live and training support services. Historically, all of these fees are billed upfront and recorded as deferred revenue until the implementation was complete, and then, as the service does not have stand-alone value, it is 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. Previously deferred revenue balances related to implementation services that were billed up front and did not have stand alone value, will continue to be amortized over those remaining customer lives. Also, in 2014, 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.
	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 Expenses	Direct Operating Expense – Direct operating expense consists primarily of compensation expense (including stock-based compensation) related to personnel who provide services, including implementation go-live and training of clients, and claim processing costs. We expense these 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 Expenses	Research and Development Expense – Research and development expense consists primarily of compensation expense for research and development employees (including stock-based compensation) and consulting fees for third-party developers. All such costs are expensed as incurred, except for certain internal use software development costs, which may be capitalized. Research and development expense does not include allocated amounts for rent, occupancy costs, depreciation, or amortization.
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. All investments, except for certain investments in privately-held companies which are accounted for at cost, are held as available-for-sale investments. Scheduled maturity dates of U.S. government-backed securities, corporate bonds and commercial paper purchased that are within one year are classified as short-term. Scheduled maturity dates of U.S. government-backed securities, corporate bonds and commercial paper that are in excess of one year are classified as long-term. All investments are recorded at fair value with unrealized holding gains and losses included in accumulated other comprehensive (loss) income. There were no material realized gains and losses on sales of these investments for the periods presented. The Company determines realized gains and losses based on the specific identification method.
Accounts Receivable	Accounts Receivable – Accounts receivable represents 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. Equipment, furniture, and fixtures are depreciated using the straight-line method over their estimated useful lives, generally ranging from three to five 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. Buildings are depreciated using the straight-line method over 30 to 40 years. Building improvements are depreciated using the straight-line method over 10 to 25 years. Aircraft and land improvements are depreciated using the straight-line method over 20 years and 10 years, respectively. Costs associated with maintenance and repairs are expensed as incurred.
Capitalized Interest Cost	Capitalized Interest Cost – Interest costs related to major capital projects, specifically the Company’s corporate headquarters campus project and capitalized internal-use software development costs, are capitalized until the 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 costs related to athenaNet services and certain other projects for internal use incurred during the application development stage, including stock-based compensation expense for employees 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 three years.
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, used to measure the amount of impairment loss, 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, customer backlog, non-compete agreements and customer relationships 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 cash payments are recorded 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 is 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 estimated 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.
Business Combinations	Business Combinations – We apply business combination accounting when we have acquired control over one or more businesses. Business combinations are accounted for at fair value. The associated acquisition costs are generally expensed as incurred and recorded in general and administrative expenses; non-controlling interests are reflected at fair value at the acquisition date; in-process research and development is recorded at fair value as an intangible asset at the acquisition date; restructuring costs associated with a business combination are generally expensed rather than capitalized; 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 will 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, including contingent consideration, are based on management’s estimates and assumptions, as well as other information compiled by management, 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 transactions described in Note 2.
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.
	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 to reduce non-income taxes as a grant. Credits which are expected to be used to reduce non-income taxes are recognized when the requirements to earn the credits have been met.
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 are 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.
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.
New Accounting Pronouncements	Recent Accounting Pronouncements – In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update (“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, the ASU 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). We are currently in the process of evaluating this new guidance. This guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. Early application is not permitted.

NATURE_OF_OPERATIONS_AND_SUMMA2

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Activity in the Allowance for Doubtful Accounts	Activity in the allowance for doubtful accounts is as follows:
		Years Ended December 31,
		2014			2013			2012
	Beginning balance	$	1,691		$	1,771		$	2,348
	Provision	(769		)	791			153
	Write-offs	(365		)	(871		)	(730		)
	Ending balance	$	557		$	1,691		$	1,771
Accrued Expenses	Accrued expenses consist of the following:
		As of December 31,
		2014			2013
	Accrued bonus	$	38,938		$	25,013
	Accrued vacation	8,106			5,107
	Accrued payroll	19,846			8,611
	Accrued commissions	4,878			5,713
	Accrued compensation expenses	$	71,768		$	44,444
	Accrued expenses	$	31,162		$	23,775
	Accrued property and equipment additions	5,871			605
	Accrued expenses	$	37,033		$	24,380

ACQUISITIONS_Tables

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustments	The unaudited pro forma financial information is as follows:
		Year Ended December 31,
		2013			2012
	Revenue	$	614,775		$	538,030
	Net loss	$	(1,808	)	$	(4,700	)
	Net loss per share – Basic	$	(0.05	)	$	(0.13	)
	Net loss per share – Diluted	$	(0.05	)	$	(0.13	)
Arsenal on the Charles
Business Acquisition [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the estimated fair values of assets acquired and liabilities assumed as of the date of acquisition:
	Prepaid expenses and other current assets	$	685
	Property, equipment and buildings	144,071
	Purchased intangible assets	25,545
	Accrued expenses	(271		)
	Deferred revenue	(789		)
	Other long-term liabilities	(1,916		)
	Total identifiable net assets	$	167,325
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The following table sets forth the fair value of the components of the identifiable intangible assets acquired by asset class:
	Above market leases		$	3,298
	In-place leases		22,247
	Total intangible assets subject to amortization		$	25,545
Business Acquisition, Pro Forma Information	The amounts of third-party tenant revenue (included in the line item “Implementation and other”) and net (loss) from the Arsenal on the Charles included in our Consolidated Statements of Income from the acquisition date of May 10, 2013 through the periods ended December 31, 2013 and December 31, 2014 are as follows:
		Year ended December 31, 2014			May 10, 2013 through December 31, 2013
	Third-party tenant revenue	$	14,254		$	9,738
	Net (loss)	$	(8,739	)	$	(4,827	)
Epocrates Inc
Business Acquisition [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the preliminary and final fair values of assets acquired and liabilities assumed as of the date of acquisition, March 12, 2013, and upon completion of the valuation at December 31, 2013:
		12-Mar-13			Adjustments			31-Dec-13
	Accounts receivable	$	23,144		$	(1,116	)	$	22,028
	Other current and long-term assets	3,833			650			4,483
	Property, equipment and capitalized software costs	4,168			20			4,188
	Purchased intangible assets	139,900			(500		)	139,400
	Current liabilities	(11,054		)	(282		)	(11,336		)
	Deferred tax liabilities, net	(39,811		)	(1,340		)	(41,151		)
	Deferred revenue	(29,400		)	648			(28,752		)
	Other long-term liabilities	(1,259		)	53			(1,206		)
	Total identifiable net assets	89,521			(1,867		)	87,654
	Goodwill	148,093			1,867			149,960
		$	237,614		$	—		$	237,614
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The following table sets forth the components of the identifiable intangible assets acquired by asset class and their estimated useful lives as of the date the fair values were finalized:
		Fair Value			Useful Life
	Physician network	104,000			14 years
	Drug information content	10,000			5 years
	Trade name	11,500			10 years
	Customer backlog	2,900			1.5 years
	Developed technology	6,500			3 years
	Epocrates non-compete agreement	4,500			1.5 years
	Total intangible assets subject to amortization	$	139,400
Business Acquisition, Pro Forma Information	The amounts of revenue and net income (loss) of Epocrates included in our Consolidated Statements of Income from the acquisition date of March 12, 2013 through the period ended December 31, 2013 and for the period ended December 31, 2014 are as follows:
		Year ended December 31, 2014			March 12, 2013 through December 31, 2013
	Revenue	$	44,442		$	52,380
	Net income (loss)	(a)			$	(14,447	)
	(a) As we have fully integrated our operations, it is impracticable for us to disclose the net income (loss) associated with the acquired business for the year ended December 31, 2014
Schedule of Business Acquisitions, by Acquisition	The acquisition date fair value of the consideration transferred for Epocrates, less cash and short-term investments acquired, was approximately $237.6 million, which consisted of the following:
	Cash payments	$	294,632
	Fair value of vested stock options and restricted stock units assumed	13,028
	Fair value of total consideration	307,660
	Less cash acquired	(51,796		)
	Less short-term investments acquired	(18,250		)
	Total	$	237,614
Business Acquisition, Schedule Of Integration Costs	The following table summarizes these amounts on the Consolidated Statements of Income for the years ended December 31, 2013 and 2014:
	Rollforward of integration costs
	Beginning balance, January 1, 2013	$	—
	Addition to provision	3,909
	Cash payments	(3,574		)
	Ending balance, December 31, 2013	$	335
	Reversal to provision	(42		)
	Cash payments	(293		)
	Ending balance, December 31, 2014	$	—

NET_LOSS_INCOME_PER_SHARE_Tabl

NET (LOSS) INCOME PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
NET (LOSS) INCOME PER SHARE	The following table reconciles the weighted average shares outstanding for basic and diluted net (loss) income per share for the periods indicated:
		Years Ended December 31,
		2014			2013		2012
	Net (loss) income	$	(3,119	)	$	2,594	$	18,732
	Weighted average shares used in computing basic net (loss) income per share	37,862			36,856		35,956
	Net (loss) income per share – basic	$	(0.08	)	$	0.07	$	0.52
	Net (loss) income	$	(3,119	)	$	2,594	$	18,732
	Weighted average shares used in computing basic net (loss) income per share	37,862			36,856		35,956
	Effect of dilutive securities	—			1,401		1,177
	Weighted average shares used in computing diluted net (loss) income per share	37,862			38,257		37,133
	Net (loss) income per share – diluted	$	(0.08	)	$	0.07	$	0.5

FAIR_VALUE_OF_FINANCIAL_INSTRU1

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
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, 2014 and December 31, 2013, 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.
			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 (a)		$	—	$	(244	)	$	—	$	(244	)
	Total liabilities		$	—	$	(244	)	$	—	$	(244	)
			Fair Value Measurements as of December 31, 2013, Using
			Level 1		Level 2			Level 3		Total
	Cash and cash equivalents:
	Money market funds		$	26	$	—		$	—	$	26
	Total assets		$	26	$	—		$	—	$	26
	Interest rate swap liability (a)		$	—	$	(354	)	$	—	$	(354	)
	Total liabilities		$	—	$	(354	)	$	—	$	(354	)
	(a)	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 the Company's financial instruments measured at fair value using unobservable inputs (Level 3) as of each of the years ended December 31, 2014 and 2013:
			Fair Value Measurements Using Unobservable Inputs (Level 3)
			Year Ended December 31, 2014		Year Ended December 31, 2013
	Balance beginning of period		$	—	$	448
	Payments		—		(524		)
	Additions		750		—
	Change in fair value (included in G&A expenses)		—		76
	Balance end of period		$	750	$	—

INVESTMENTS_Tables

INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Schedule of Available-for-sale Securities Reconciliation	We had the following available-for-sale securities as of December 31, 2014:
		Cost		Gross		Fair Value
				Unrealized Gain
	Marketable equity securities	$	1,100	$	39,850	$	40,950

PROPERTY_AND_EQUIPMENT_Tables

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and equipment	Property and equipment consist of the following:
		Years Ended December 31,
		2014			2013
	Equipment	$	93,583		$	78,616
	Furniture and fixtures	14,760			8,822
	Leasehold improvements	18,113			3,104
	Aircraft	15,054			3,156
	Building	131,746			136,368
	Building improvements	49,671			24,441
	Land	23,059			23,059
	Land improvements	4,339			2,980
	Total property and equipment, at cost	350,325			280,546
	Accumulated depreciation and amortization	(96,416		)	(72,777		)
	Construction in progress	17,643			5,249
	Property and equipment, net	$	271,552		$	213,018

GOODWILL_AND_PURCHASED_INTANGI1

GOODWILL AND PURCHASED INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2014
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, 2014 and 2013:
	Gross balance as of January 1, 2013	$	48,090
	Goodwill recorded in connection with the acquisition of Epocrates, Inc.	149,959
	Gross balance as of December 31, 2013	$	198,049
	Gross balance as of December 31, 2014	$	198,049
Schedule of Acquired Finite-Lived Intangible Assets by Major Class	ntangible assets acquired as of December 31, 2014 and 2013 are as follows:
			December 31, 2014
			Gross		Accumulated			Net		Weighted Average Remaining
					Amortization					Useful Life (years)
	Developed technology		$	9,721	$	(6,294	)	$	3,427	1.1
	Customer relationships		21,434		(9,555		)	11,879		5.7
	Doctor network		104,000		(9,792		)	94,208		12.2
	Drug information content		10,000		(3,608		)	6,392		3.2
	Trade name		11,500		(2,074		)	9,426		8.2
	Non-compete agreement		1,178		(873		)	305		0.8
	Above market leases		3,016		(916		)	2,100		1.6
	Leases in place		19,695		(8,065		)	11,630		3.9
	Total		$	180,544	$	(41,177	)	$	139,367
			December 31, 2013
			Gross		Accumulated			Net		Weighted Average Remaining
					Amortization					Useful Life (years)
	Developed technology		$	11,721	$	(4,737	)	$	6,984	2
	Customer relationships		21,434		(7,365		)	14,069		6.6
	Doctor network		104,000		(682		)	103,318		13.2
	Drug information content		10,000		(1,608		)	8,392		4.2
	Trade name		11,500		(924		)	10,576		9.2
	Customer backlog		2,900		(1,554		)	1,346		0.7
	Non-compete agreement		6,178		(3,280		)	2,898		1
	Above market leases		3,123		(357		)	2,766		5.9
	Leases in place		21,578		(3,563		)	18,015		5.3
	Total		$	192,434	$	(24,070	)	$	168,364
Schedule of Finite Lived Intangible Assets Future Amortization Expense	Estimated amortization expense, based upon our intangible assets at December 31, 2014, is as follows:
	Year ending December 31,	Amount
	2015	$	20,272
	2016	16,240
	2017	15,743
	2018	14,324
	2019	13,941
	Thereafter	58,847
	Total	$	139,367

OPERATING_LEASES_AND_OTHER_COM1

OPERATING LEASES AND OTHER COMMITMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Leases [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Future minimum lease payments under non-cancelable operating leases as of December 31, 2014 are as follows:
	Year ending December 31,	Future Rent
		Payments
	2015	$	7,994
	2016	12,878
	2017	12,457
	2018	12,238
	2019	11,789
	Thereafter	88,008
	Total minimum lease payments	$	145,364

DEBT_Tables

DEBT (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt	Future principal payments of the unsecured term loan facility at December 31, 2014 are as follows:
		Amount
	2015	$	15,000
	2016	15,000
	2017	15,000
	2018	128,750
	Total	$	173,750
	Less current portion	15,000
	Long-term portion	$	158,750
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The fair value of the interest rate swap recognized in other long-term liabilities and in OCI was as follows:
							Fair Value
	Effective Date	Notional Amount		Fixed Rate		Maturity	December 31, 2014			December 31, 2013
	August 31, 2013	120,000		0.8396	%	August 31, 2016	$	(244	)	$	(354	)

STOCKBASED_COMPENSATION_Tables

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2014
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, 2014, 2013, and 2012 is as follows:
		Year Ended December 31,
		2014				2013			2012
	Stock-based compensation charged to:
	Direct operating	$	12,009			$	7,778		$	5,619
	Selling and marketing	14,581				12,057			7,717
	Research and development	7,221				4,238			3,213
	General and administrative	21,747				18,575			10,687
	Total	$	55,558			$	42,648		$	27,236
	Amortization of capitalized stock-based compensation related to software development	2,258				1,027			257
	Total	$	57,816			$	43,675		$	27,493
Schedule of Share-based Compensation, Stock Options, Activity	The following table presents the stock option activity for the year ended December 31, 2014:
		Shares			Weighted-			Weighted-		Aggregate
					Average			Average		Intrinsic
					Exercise			Remaining		Value
					Price			Contractual Term
								(in years)
	Outstanding – January 1, 2014	2,167			$	48.69
	Granted	188			183.36
	Exercised	(470	)		35.08
	Forfeited	(35	)		87.24
	Outstanding – as of December 31, 2014	1,850			65.14			6		$	156,804
	Exercisable – as of December 31, 2014	1,235			$	43.5		5		$	126,318
	Vested and expected to vest as of December 31, 2014	1,754			$	61.87		5.9		$	153,142
	Weighted-average fair value of options granted for the year ended December 31, 2014				$	77.55
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,
		2014		2013		2012
	Risk-free interest rate	.66% - 1.67%		.35% - .75%		1.00%
	Expected dividend yield	—%		—%		—%
	Expected option term (years)	3.0 - 5.0		3.0 - 5.0		3.0 - 5.0
	Expected stock volatility	46% - 47%		41% - 45%		43% - 52%
Schedule of Nonvested Restricted Stock Units Activity	The following table presents the restricted stock unit activity for the year ended December 31, 2014:
		Shares			Weighted-
					Average
					Grant
					Date
					Fair Value
	Outstanding – January 1, 2014	1,193			$	75.2
	Granted	556			181.81
	Vested	(452	)		67.39
	Forfeited	(87	)		109.94
	Outstanding – as of December 31, 2014	1,210			$	124.65

INCOME_TAXES_Tables

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Current Foreign Tax Expense (Benefit)	The components of our income tax benefit (provision) for the years ended December 31, 2014, 2013, and 2012 are as follows:
		2014				2013				2012
	Current Benefit (Provision):
	Federal	$	(9,656	)		$	(4,225	)		$	(13,089	)
	State	(884		)		(1,495		)		(3,575		)
	Foreign	(385		)		(961		)		(372		)
		(10,925		)		(6,681		)		(17,036		)
	Deferred Benefit (Provision):
	Federal	10,695				5,291				(26		)
	State	906				1,753				802
	Foreign	69				—				114
		11,670				7,044				890
	Total income tax benefit (provision)	$	745			$	363			$	(16,146	)
Schedule of Deferred Tax Assets and Liabilities	The components of the Company’s deferred income taxes as of December 31, 2014 and 2013 are as follows:
		2014				2013
	Deferred tax assets:
	Federal net operating loss carryforward	$	—			$	187
	State net operating loss carryforward	1,694				1,476
	Research and development tax credits	3,328				3,244
	Allowances for accounts receivable	1,168				2,773
	Deferred rent obligation	7,555				328
	Stock compensation	25,264				18,270
	Other accrued liabilities	2,223				2,171
	Deferred revenue	17,797				17,754
	Other	1,473				3,101
	Total gross deferred tax assets	60,502				49,304
	Valuation allowance	(3,420		)		(2,627		)
	Total deferred tax assets	57,082				46,677
	Deferred tax liabilities:
	Intangible assets	(40,463		)		(49,555		)
	Capitalized software development	(15,769		)		(8,641		)
	Property and equipment	(4,621		)		(3,784		)
	Investments	(14,913		)		—
	Total deferred tax liabilities	(75,766		)		(61,980		)
	Net deferred tax (liabilities) assets	$	(18,684	)		$	(15,303	)
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, 2014, 2013, and 2012:
		2014			2013			2012
	Income tax computed at federal statutory tax rate	35	%		35	%		35	%
	State taxes, net of federal benefit	6	%		(6	)%		5	%
	Research and development credits	86	%		(98	)%		—	%
	Permanent differences	(87	)%		20	%		6	%
	Valuation allowance	(21	)%		33	%		—	%
	Total	19	%		(16	)%		46	%
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:
		2014				2013				2012
	Beginning uncertain tax benefits	$	4,851			$	1,761			$	1,685
	Prior year – decreases	(79		)		(537		)		(140		)
	Prior year – increases	887				501				177
	Acquired balances	—				2,339				—
	Current year - decreases	(212		)		—				—
	Current year – increases	366				787				39
	Ending uncertain tax benefits	$	5,813			$	4,851			$	1,761

QUARTERLY_FINANCIAL_INFORMATIO1

QUARTERLY FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Selected quarterly financial information follows for the year ended December 31, 2014:
		First			Second			Third			Fourth			Year
		Quarter			Quarter			Quarter			Quarter
	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
	Selected quarterly financial information follows for the year ended December 31, 2013:
		First			Second			Third			Fourth			Year
		Quarter			Quarter			Quarter			Quarter
	Revenue:
	Business services	$	121,463		$	137,919		$	141,326		$	162,529		$	563,237
	Implementation and other	4,133			8,382			10,201			9,050			31,766
	Total revenue	125,596			146,301			151,527			171,579			595,003
	Expense:
	Direct operating	53,185			59,390			63,245			62,852			238,672
	Selling and marketing	32,922			41,035			37,584			37,947			149,488
	Research and development	11,944			14,269			15,104			16,322			57,639
	General and administrative	31,077			24,670			21,690			22,339			99,776
	Depreciation and amortization	8,341			11,107			11,263			12,864			43,575
	Total expense	137,469			150,471			148,886			152,324			589,150
	Operating (loss) income	(11,873		)	(4,170		)	2,641			19,255			5,853
	Other (expense) income:
	Interest expense	(164		)	(1,001		)	(1,421		)	(1,319		)	(3,905		)
	Other (expense) income	54			63			30			136			283
	Total other expense	(110		)	(938		)	(1,391		)	(1,183		)	(3,622		)
	(Loss) income before income tax benefit (provision)	(11,983		)	(5,108		)	1,250			18,072			2,231
	Income tax benefit (provision)	12,683			(7,313		)	(80		)	(4,927		)	363
	Net income (loss)	$	700		$	(12,421	)	$	1,170		$	13,145		$	2,594
	Net income (loss) per share – Basic	$	0.02		$	(0.34	)	$	0.03		$	0.35		$	0.07
	Net income (loss) per share – Diluted	$	0.02		$	(0.34	)	$	0.03		$	0.34		$	0.07
	Weighted average shares used in computing net income (loss) per share:
	Basic	36,409			36,760			36,970			37,262			36,856
	Diluted	37,744			36,760			38,343			38,645			38,257

NATURE_OF_OPERATIONS_AND_SUMMA3

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Additional Information (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	service
	Business
	Segment
Significant Accounting Policies [Line Items]
Number of acquired and integrated businesses	2
Number of operating segments	1
Number of integrated services	4
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	$15,500,000	$14,200,000	$12,300,000
Restricted cash	0	3,000,000
Software amortization expense	28,600,000	17,900,000	3,400,000
Future amortization expense for software development, year one	20,272,000
Future amortization expense for software development, year two	16,240,000
Future amortization expense for software, year three	15,743,000
Impairment losses recognized	0	0	0
Related party transaction, total expense	11,300,000	1,500,000
Related party transaction, total payable	1,300,000	400,000
Developed technology
Significant Accounting Policies [Line Items]
Software amortization expense	33,200,000	18,000,000	9,000,000
Future amortization expense for software development, year one	34,600,000
Future amortization expense for software development, year two	17,400,000
Future amortization expense for software, year three	2,700,000
Balance in capitalization in progress account related to software development costs	$1,700,000
Aircraft
Significant Accounting Policies [Line Items]
Property and Equipment, useful life (in years)	20 years
Land improvements
Significant Accounting Policies [Line Items]
Property and Equipment, useful life (in years)	10 years
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]
Property and Equipment, useful life (in years)	3 years
Minimum | Building
Significant Accounting Policies [Line Items]
Property and Equipment, useful life (in years)	30 years
Minimum | Building improvements
Significant Accounting Policies [Line Items]
Property and Equipment, useful life (in years)	10 years
Maximum | Developed technology
Significant Accounting Policies [Line Items]
Estimated useful life of the software (in years)	3 years
Maximum | Furniture Fixtures And Equipment
Significant Accounting Policies [Line Items]
Property and Equipment, useful life (in years)	5 years
Maximum | Building
Significant Accounting Policies [Line Items]
Property and Equipment, useful life (in years)	40 years
Maximum | Building improvements
Significant Accounting Policies [Line Items]
Property and Equipment, useful life (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

NATURE_OF_OPERATIONS_AND_SUMMA4

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Activity in Allowance for Doubtful Accounts) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$1,691	$1,771	$2,348
Provision	-769	791	153
Write-offs	-365	-871	-730
Ending balance	$557	$1,691	$1,771

NATURE_OF_OPERATIONS_AND_SUMMA5

NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Accrued Expenses) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued bonus	$38,938	$25,013
Accrued vacation	8,106	5,107
Accrued payroll	19,846	8,611
Accrued commissions	4,878	5,713
Accrued compensation expenses	71,768	44,444
Accrued expenses	31,162	23,775
Accrued property and equipment additions	5,871	605
Accrued expenses	$37,033	$24,380

ACQUISITIONS_Schedule_of_Recog

ACQUISITIONS (Schedule of Recognized Assets Acquired and Liabilities Assumed) (Details) (USD $)	10 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012	10-May-13	Mar. 12, 2013
Business Acquisition [Line Items]
Goodwill	$198,049	$198,049	$48,090
Arsenal on the Charles
Business Acquisition [Line Items]
Prepaid expenses and other current assets				685
Property, equipment and buildings				144,071
Purchased intangible assets				25,545
Accrued expenses				-271
Deferred revenue				-789
Other long-term liabilities				-1,916
Total identifiable net assets				167,325
Epocrates Inc
Business Acquisition [Line Items]
Property, equipment and buildings	4,188				4,168
Purchased intangible assets	139,400				139,900
Accrued expenses	-11,336				-11,054
Deferred revenue	-28,752				-29,400
Other long-term liabilities	-1,206				-1,259
Total identifiable net assets	87,654				89,521
Accounts receivable	22,028				23,144
Other current and long-term assets	4,483				3,833
Deferred tax liabilities, net	-41,151				-39,811
Goodwill	149,960				148,093
Fair value of assets acquired and liabilities assumed	237,614				237,614
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Accounts receivable, Adjustments	-1,116
Other current and long-term assets, Adjustments	650
Property, equipment and capitalized software, Adjustments	20
Purchased intangible assets, Adjustments	-500
Current liabilities, Adjustments	-282
Deferred tax liabilities, net, Adjustments	-1,340
Deferred revenue, Adjustments	648
Other long-term liabilities, Adjustments	53
Total identifiable net assets, Adjustments	-1,867
Goodwill, Adjustments	1,867
Fair value of assets acquired and liabilities assumed, Adjustments	$0

ACQUISITIONS_Total_Considerati

ACQUISITIONS (Total Consideration as of Acquisition Date) (Details) (Epocrates Inc, USD $)	0 Months Ended
In Thousands, unless otherwise specified	Mar. 12, 2013	Mar. 12, 2013
Epocrates Inc
Business Acquisition [Line Items]
Cash payments	$294,632
Fair value of vested stock options and restricted stock units assumed	13,028
Fair value of total consideration	307,660	307,660
Less cash acquired	-51,796	-51,796
Less short-term investments acquired	-18,250	-18,250
Total	$237,614

ACQUISITIONS_Business_Acquisit

ACQUISITIONS (Business Acquisition, Pro Forma Information) (Details) (USD $)	8 Months Ended	12 Months Ended	10 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Arsenal on the Charles
Business Acquisition [Line Items]
Third party tenant revenue	$9,738	$14,254
Net loss	-4,827	-8,739
Epocrates Inc
Business Acquisition [Line Items]
Third party tenant revenue		44,442	52,380
Net loss			($14,447)

ACQUISITIONS_Schedule_of_Ident

ACQUISITIONS (Schedule of Identifiable Intangible Assets Acquired) (Details) (USD $)	12 Months Ended		3 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013
Above market leases
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	1 year 7 months 6 days	5 years 10 months 24 days
In-place leases
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	3 years 10 months 24 days	5 years 3 months 18 days
Doctor network
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	12 years 2 months 12 days	13 years 2 months 12 days
Drug information content
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	3 years 2 months 12 days	4 years 2 months 12 days
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	8 years 2 months 12 days	9 years 2 months 12 days
Epocrates non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Useful Life	9 months 18 days	1 year
Arsenal on the Charles
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization			$25,545
Arsenal on the Charles | Above market leases
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization			3,298
Arsenal on the Charles | In-place leases
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization			22,247
Epocrates Inc
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization				139,400
Epocrates Inc | Doctor network
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization				104,000
Useful Life				14 years
Epocrates Inc | Drug information content
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization				10,000
Useful Life				5 years
Epocrates Inc | Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization				11,500
Useful Life				10 years
Epocrates Inc | Customer backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization				2,900
Useful Life				1 year 6 months
Epocrates Inc | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization				6,500
Useful Life				3 years
Epocrates Inc | Epocrates non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Total intangible assets subject to amortization				$4,500
Useful Life				1 year 6 months

ACQUISITIONS_Schedule_of_Integ

ACQUISITIONS (Schedule of Integration Costs) (Details) (Epocrates Inc, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Epocrates Inc
Integration Costs [Roll Forward]
Beginning Balance	$335	$0
Addition (reversal) to provision	-42	3,909
Cash payments	-293	-3,574
Ending Balance	$0	$335

ACQUISITIONS_Additional_Inform

ACQUISITIONS (Additional Information) (Narrative) (Details) (USD $)	12 Months Ended			0 Months Ended	8 Months Ended	36 Months Ended	0 Months Ended	10 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	10-May-13	Dec. 31, 2013	Dec. 31, 2013	Mar. 12, 2013	Dec. 31, 2013
Business Acquisition [Line Items]
Stock-based compensation expense	$55,558,000	$42,648,000	$27,236,000
Arsenal on the Charles
Business Acquisition [Line Items]
Number of acres				29
Cash payments				168,500,000
Total				167,300,000
Direct operating expenses	13,600,000				9,100,000
Transactions costs incurred in connection with acquisition		2,400,000				3,100,000
Epocrates Inc
Business Acquisition [Line Items]
Cash payments							294,632,000
Total							237,614,000
Transactions costs incurred in connection with acquisition		2,700,000				3,200,000
Share conversion ratio							0.1239
Fair value of assumed stock options and restricted stock units							22,600,000
Amount allocated to purchase consideration							13,028,000
Amount of fair value of stock options and restricted stock units allocated to future services							9,600,000
Stock-based compensation expense	300,000							7,400,000
Stock based compensation expense primarily related to acceleration of certain stock awards								$7,900,000

ACQUISITIONS_Schedule_of_Pro_F

ACQUISITIONS (Schedule of Pro Forma Information) (Details) (Epocrates Inc and the Arsenal on the Charles, USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Epocrates Inc and the Arsenal on the Charles
Business Acquisition [Line Items]
Revenue	$614,775	$538,030
Net loss	($1,808)	($4,700)
Net loss per share – Basic	($0.05)	($0.13)
Net loss per share – Diluted	($0.05)	($0.13)

NET_LOSS_INCOME_PER_SHARE_Reco

NET (LOSS) INCOME PER SHARE (Reconciliation of Weighted Average Shares Outstanding for Basic and Diluted Net Income Per Share) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net (loss) income	$8,729	($1,631)	($2,162)	($8,055)	$13,145	$1,170	($12,421)	$700	($3,119)	$2,594	$18,732
Weighted average shares used in computing basic net (loss) income per share	38,097	37,999	37,860	37,484	37,262	36,970	36,760	36,409	37,862	36,856	35,956
Net (loss) income per share – basic	$0.23	($0.04)	($0.06)	($0.21)	$0.35	$0.03	($0.34)	$0.02	($0.08)	$0.07	$0.52
Effect of dilutive securities									0	1,401	1,177
Weighted average shares used in computing diluted net (loss) income per share	39,040	37,999	37,860	37,484	38,645	38,343	36,760	37,744	37,862	38,257	37,133
Net (loss) income per share – diluted	$0.22	($0.04)	($0.06)	($0.21)	$0.34	$0.03	($0.34)	$0.02	($0.08)	$0.07	$0.50

NET_LOSS_INCOME_PER_SHARE_Net_

NET (LOSS) INCOME PER SHARE (Net (loss) Income Per Share - Additional Information) (Detail)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Options and restricted stock units which have an antidilutive effect (shares)	0.4	0.4

FAIR_VALUE_OF_FINANCIAL_INSTRU2

FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value of Financial Instruments - Narrative (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	10-May-13
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	$1,100,000
Available-for-sale Securities	40,950,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax	-39,850,000
Unrealized gain (loss) on securities, tax	15,005,000	5,000	3,000
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	0	0
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness	0	0
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value		0
Senior Credit Facility | Unsecured Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amount outstanding on facility	173,800,000	188,800,000		200,000,000
Senior Credit Facility | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amount outstanding on facility	35,000,000	35,000,000		50,000,000
Prepaid Expenses and Other Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes Receivable, Fair Value Disclosure	800,000
Designated as Hedging Instrument | Other Long Term Liabilities | Interest Rate Swap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of swap recognized	$244,000	$354,000

FAIR_VALUE_OF_FINANCIAL_INSTRU3

FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value of Financial Instruments - Fair Value, Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	$40,950
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	41,700		26
Interest rate swap liability	-244	[1]	-354	[1]
Total liabilities	-244		-354
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	40,950		26
Interest rate swap liability	0	[1]	0	[1]
Total liabilities	0		0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0		0
Interest rate swap liability	-244	[1]	-354	[1]
Total liabilities	-244		-354
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	750		0
Interest rate swap liability	0	[1]	0	[1]
Total liabilities	0		0
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
Marketable equity securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	40,950
Marketable equity securities | Fair Value, Measurements, Recurring | Fair Value, Inputs, 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 | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	0
MDP Accelerator portfolio | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	750
MDP Accelerator portfolio | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	0
MDP Accelerator portfolio | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	0
MDP Accelerator portfolio | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	750
Money market funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds			26
Money market funds | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds			26
Money market funds | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds			0
Money market funds | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds			$0
[1]	Recorded in other long-term liabilities on the Consolidated Balance Sheets.

FAIR_VALUE_OF_FINANCIAL_INSTRU4

FAIR VALUE OF FINANCIAL INSTRUMENTS Fair Value of Financial Instruments - Reconciliations for Fair Values of Financial Instruments Determined by Level 3 (Details) (MDP Accelerator portfolio, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
MDP Accelerator portfolio
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance beginning of period	$0	$448
Payments	0	-524
Additions	750	0
Change in fair value (included in G&A expenses)	0	76
Balance end of period	$750	$0

INVESTMENTS_Summary_of_Availab

INVESTMENTS (Summary of Available-For-Sale Securities) (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Investments [Abstract]
Amortized Cost	$1,100
Gross Unrealized Gains	39,850
Fair Value	$40,950

PROPERTY_AND_EQUIPMENT_Additio

PROPERTY AND EQUIPMENT (Additional Information) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Capital leases	$0	$0
Property and equipment, depreciation expense	31,500,000	25,500,000	16,600,000
Arsenal on the Charles
Property, Plant and Equipment [Line Items]
Fair value of buildings acquired	121,300,000
Fair value of land and land improvements acquired	21,000,000
Fair value of land improvements	$1,800,000

PROPERTY_AND_EQUIPMENT_Schedul

PROPERTY AND EQUIPMENT (Schedule of Property and Equipment) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$350,325	$280,546
Accumulated depreciation and amortization	-96,416	-72,777
Construction in progress	17,643	5,249
Property and equipment, net	271,552	213,018
Equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	93,583	78,616
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	14,760	8,822
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	18,113	3,104
Aircraft
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	15,054	3,156
Building
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	131,746	136,368
Building improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	49,671	24,441
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	$4,339	$2,980

GOODWILL_AND_PURCHASED_INTANGI2

GOODWILL AND PURCHASED INTANGIBLE ASSETS (Additional Information) (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$28.60	$17.90	$3.40
Licensing Agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived License Agreements	$0.10

GOODWILL_AND_PURCHASED_INTANGI3

GOODWILL AND PURCHASED INTANGIBLE ASSETS (Activity Relating to Carrying Values of Goodwill) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012	Mar. 12, 2013
Goodwill [Roll Forward]
Beginning gross balance		$198,049	$48,090
Ending gross balance	198,049	198,049	48,090
Epocrates Inc
Goodwill [Roll Forward]
Beginning gross balance				148,093
Goodwill recorded during the period	149,959
Ending gross balance	$149,960			$148,093

GOODWILL_AND_PURCHASED_INTANGI4

GOODWILL AND PURCHASED INTANGIBLE ASSETS (Intangible Assets Acquired) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	$180,544	$192,434
Accumulated Amortization	-41,177	-24,070
Net	139,367	168,364
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	9,721	11,721
Accumulated Amortization	-6,294	-4,737
Net	3,427	6,984
Weighted Average Remaining Useful Life (years)	1 year 1 month 6 days	2 years
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	21,434	21,434
Accumulated Amortization	-9,555	-7,365
Net	11,879	14,069
Weighted Average Remaining Useful Life (years)	5 years 8 months 12 days	6 years 7 months 6 days
Doctor network
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	104,000	104,000
Accumulated Amortization	-9,792	-682
Net	94,208	103,318
Weighted Average Remaining Useful Life (years)	12 years 2 months 12 days	13 years 2 months 12 days
Drug information content
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	10,000	10,000
Accumulated Amortization	-3,608	-1,608
Net	6,392	8,392
Weighted Average Remaining Useful Life (years)	3 years 2 months 12 days	4 years 2 months 12 days
Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	11,500	11,500
Accumulated Amortization	-2,074	-924
Net	9,426	10,576
Weighted Average Remaining Useful Life (years)	8 years 2 months 12 days	9 years 2 months 12 days
Customer backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Gross		2,900
Accumulated Amortization		-1,554
Net		1,346
Weighted Average Remaining Useful Life (years)		8 months 12 days
Non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	1,178	6,178
Accumulated Amortization	-873	-3,280
Net	305	2,898
Weighted Average Remaining Useful Life (years)	9 months 18 days	1 year
Above market leases
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	3,016	3,123
Accumulated Amortization	-916	-357
Net	2,100	2,766
Weighted Average Remaining Useful Life (years)	1 year 7 months 6 days	5 years 10 months 24 days
Leases in place
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	19,695	21,578
Accumulated Amortization	-8,065	-3,563
Net	$11,630	$18,015
Weighted Average Remaining Useful Life (years)	3 years 10 months 24 days	5 years 3 months 18 days

GOODWILL_AND_PURCHASED_INTANGI5

GOODWILL AND PURCHASED INTANGIBLE ASSETS (Estimated Amortization Expense) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]
2015	$20,272
2016	16,240
2017	15,743
2018	14,324
2019	13,941
Thereafter	58,847
Net	$139,367	$168,364

OPERATING_LEASES_AND_OTHER_COM2

OPERATING LEASES AND OTHER COMMITMENTS (Additional Information) (Detail) (USD $)	1 Months Ended		12 Months Ended
In Millions, unless otherwise specified	31-May-11	Jun. 30, 2005	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
			location
Operating Leased Assets [Line Items]
Allowances for the leasehold improvements for the office space and reimbursement of moving costs		$11.50
Repayment of incentive allowance	2.1
Number of locations under operating lease			4
Operating Leases, rent expense net			9.9	5.5	4.9
General and administrative
Operating Leased Assets [Line Items]
Net gain due to early termination of lease				$2.50

OPERATING_LEASES_AND_OTHER_COM3

OPERATING LEASES AND OTHER COMMITMENTS (Future Minimum Lease Payments Under Non-cancelable Operating Leases) (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Leases [Abstract]
2015	$7,994
2016	12,878
2017	12,457
2018	12,238
2019	11,789
Thereafter	88,008
Total minimum lease payments	$145,364

DEBT_Additional_Information_De

DEBT (Additional Information) (Detail) (USD $)	0 Months Ended
	Jan. 07, 2013	Oct. 20, 2011	Jan. 03, 2013	10-May-13	Mar. 11, 2013	Dec. 31, 2014	Dec. 31, 2013	Aug. 31, 2013
Revolving Credit Agreement
Debt Instrument [Line Items]
Line of Credit, term		5 years
Line of Credit		$100,000,000			$155,000,000
Interest rate for revolving loans, Federal Funds rate		0.50%
Interest rate for revolving loans, LIBOR rate		1.00%
Additional borrowing capacity for Senior Credit Facility	55,000,000
Financing Fees	300,000
Revolving Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Amounts borrowed and repaid from revolving credit facility			100,000,000
Senior Credit Facility
Debt Instrument [Line Items]
Line of Credit, term				5 years
Additional borrowing capacity for Senior Credit Facility				100,000,000
Credit Agreement, amount				325,000,000
Senior Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Line of Credit				50,000,000		35,000,000	35,000,000
Credit Agreement, amount				125,000,000
Senior Credit Facility | Unsecured Debt
Debt Instrument [Line Items]
Line of Credit				200,000,000		173,800,000	188,800,000
Credit Agreement, amount				200,000,000
Quarterly payment amount under agreement				3,800,000
Amount available under credit facility						90,000,000
Senior Credit Facility | Senior Notes
Debt Instrument [Line Items]
Financing Fees				1,400,000
Interest rate for facility						1.16%
Interest Rate Swap | Designated as Hedging Instrument
Debt Instrument [Line Items]
Derivative, Notional Amount								$120,000,000
Derivative, Fixed Interest Rate								0.84%

DEBT_Schedule_of_Future_Paymen

DEBT (Schedule of Future Payments of Long Term Debt) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Line of Credit Facility [Line Items]
Less current portion	$15,000	$15,000
Long-term portion	158,750	173,750
Unsecured Debt | Senior Credit Facility
Line of Credit Facility [Line Items]
2015	15,000
2016	15,000
2017	15,000
2018	128,750
Total	173,750
Less current portion	15,000
Long-term portion	$158,750

DEBT_Interest_Rate_Swap_Agreem

DEBT (Interest Rate Swap Agreement) (Details) (Interest Rate Swap, Designated as Hedging Instrument, USD $)	Aug. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$120,000
Derivative, Fixed Interest Rate	0.84%
Other Long Term Liabilities
Derivatives, Fair Value [Line Items]
Fair value of swap recognized		($244)	($354)

STOCKHOLDERS_EQUITY_Additional

STOCKHOLDERS' EQUITY (Additional Information) (Detail)	Dec. 31, 2014	Dec. 31, 2013
	Vote
Class of Stock [Line Items]
Preferred Stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares outstanding	0	0
Votes per share entitled to common stockholders	1
Minimum
Class of Stock [Line Items]
Number of series	1

STOCKBASED_COMPENSATION_Additi

STOCK-BASED COMPENSATION (Additional Information) (Detail) (USD $)	12 Months Ended			0 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 12, 2013	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization of capitalized stock-based compensation related to software development	$2,258,000	$1,027,000	$257,000
Options granted vesting period	4 years
Options granted contractual term (in years)	5 years
Compensation expense	55,558,000	42,648,000	27,236,000
Unrecognized stock-based compensation expense, expected weighted-average period for recognition (in years)	2 years 6 months
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	11,700,000	14,000,000	9,800,000
Amount of fair value of stock options and restricted stock units allocated to future services	16,500,000	17,400,000
Weighted average fair value of stock options granted	$77.55	$38.09	$31.71
Intrinsic value of shares purchased	53,500,000	53,200,000	36,100,000
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	111,000,000
Unrecognized stock-based compensation expense, expected weighted-average period for recognition (in years)	2 years 8 months
Number of annual anniversary installments	4
Number of quarterly anniversary installments	4
Compensation expense, restricted stock	42,200,000	27,400,000	17,300,000
Weighted average fair value of restricted units granted	$181.81	$98.34	$71.15
Intrinsic value of vested restricted stock units	78,500,000	35,200,000	15,100,000
Epocrates Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share conversion ratio				0.1239
Amount of fair value of stock options and restricted stock units allocated to future services				9,600,000
Stock Option Plan 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in number of shares reserved for issuance (shares)		1,660,000	1,850,000		1,300,000
Multiplier of full value of awards (shares)			1.66		1.3
Share-based compensation arrangement by share-based payment award, number of shares available for grant	4,023,000	4,609,000
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
Stock Option Plan 2007 | Incentive Stock Plans
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%
Epocrates Stock Plan | Epocrates Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options assumed		400,000
Employee Stock Purchase Plan (''2007 ESPP'')
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	1,700,000	1,200,000	1,000,000
Employee stock purchase price, percentage of the closing price of common stock	85.00%
Software Development Costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation capitalized	$4,700,000	$2,200,000

STOCKBASED_COMPENSATION_Total_

STOCK-BASED COMPENSATION (Total Stock-Based Compensation Expense) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$55,558	$42,648	$27,236
Amortization of capitalized stock-based compensation related to software development	2,258	1,027	257
Total	57,816	43,675	27,493
Direct operating
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	12,009	7,778	5,619
Selling and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	14,581	12,057	7,717
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	7,221	4,238	3,213
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$21,747	$18,575	$10,687

STOCKBASED_COMPENSATION_Stock_

STOCK-BASED COMPENSATION (Stock Option Activity) (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014
Shares
Beginning balance	2,167
Granted	188
Exercised	-470
Forfeited	-35
Outstanding – as of December 31, 2014	1,850
Exercisable – as of December 31, 2014	1,235
Vested and expected to vest as of December 31, 2014	1,754
Weighted- Average Exercise Price
Beginning balance	$48.69
Granted	$183.36
Exercised	$35.08
Forfeited	$87.24
Ending balance	$65.14
Exercisable – as of December 31, 2014	$43.50
Vested and expected to vest as of December 31, 2014	$61.87
Weighted-average fair value of options granted for the year ended December 31, 2014	$77.55
Weighted- Average Remaining Contractual Term (in years)
Outstanding – as of December 31, 2014	6 years
Vested and expected to vest as of December 31, 2014	5 years
Vested and expected to vest as of December 31, 2014	5 years 10 months 24 days
Aggregate Intrinsic Value
Outstanding – as of December 31, 2014	$156,804
Exercisable – as of December 31, 2014	126,318
Vested and expected to vest as of December 31, 2014	$153,142

STOCKBASED_COMPENSATION_Weight

STOCK-BASED COMPENSATION (Weighted Average Assumptions Used to Compute Stock-based Compensation Expense for Awards Granted) (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	0.66%	0.35%	1.00%
Risk-free interest rate, maximum	1.67%	0.75%	1.00%
Expected dividend yield	0.00%	0.00%	0.00%
Expected stock volatility, minimum	46.00%	41.00%	43.00%
Expected stock volatility, maximum	47.00%	45.00%	52.00%
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

STOCKBASED_COMPENSATION_Restri

STOCK-BASED COMPENSATION (Restricted Stock Unit Activity) (Detail) (Restricted stock units, USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted stock units
Restricted stock units - Shares
Beginning Balance	1,193
Granted	556
Vested	-452
Forfeited	-87
Ending Balance	1,210	1,193
Restricted stock units - Weighted-Average Grant Date Fair Value
Beginning Balance	$75.20
Granted	$181.81	$98.34	$71.15
Vested	$67.39
Forfeited	$109.94
Ending Balance	$124.65	$75.20

INCOME_TAXES_Additional_Inform

INCOME TAXES (Additional Information) (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Tax benefit realized from stock-based awards	$9,900,000	$6,900,000	$14,100,000
Unrecognized tax benefits	5,813,000	4,851,000	1,761,000	1,685,000
Unrecognized tax benefits, if recognized, would impact effective tax rate	5,100,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	800,000	500,000
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	1,200,000	700,000
Unrecognized Tax Benefits, Accrued Interest and Penalties Adjustment, Foreign Currency Translation	300,000	100,000
Federal
Income Taxes [Line Items]
Decrease in current tax provision by utilizing operating loss carryforwards	9,900,000	7,000,000	2,800,000
Operating loss carryforwards	73,600,000	28,000,000
Unrecognized tax benefits	35,400,000
R&D credits	9,600,000
Utilization of credits under the without method of accounting related to stock-based compensation	9,600,000
Federal | Minimum
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2020
Federal | Maximum
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2034
Federal | Stock Based Compensation Expense
Income Taxes [Line Items]
Operating loss carryforwards	73,600,000	27,500,000
State
Income Taxes [Line Items]
Operating loss carryforwards	67,700,000	26,000,000
Unrecognized tax benefits	3,700,000
R&D credits	3,900,000
Utilization of credits under the without method of accounting related to stock-based compensation	1,800,000
State | Minimum
Income Taxes [Line Items]
Operating loss carryforwards, expiration year	2018
State | Stock Based Compensation Expense
Income Taxes [Line Items]
Operating loss carryforwards	$32,700,000	$1,600,000

INCOME_TAXES_Components_of_Inc

INCOME TAXES (Components of Income Tax Provision) (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current Benefit (Provision):
Federal									($9,656)	($4,225)	($13,089)
State									-884	-1,495	-3,575
Foreign									-385	-961	-372
Current Income Tax Expense (Benefit), Total									-10,925	-6,681	-17,036
Deferred Benefit (Provision):
Federal									10,695	5,291	-26
State									906	1,753	802
Foreign									69	0	114
Deferred income taxes									11,670	7,044	890
Total income tax benefit (provision)	($5,329)	$853	$739	$4,482	($4,927)	($80)	($7,313)	$12,683	$745	$363	($16,146)

INCOME_TAXES_Components_of_Def

INCOME TAXES (Components of Deferred Income Taxes) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Federal net operating loss carryforward	$0	$187
State net operating loss carryforward	1,694	1,476
Research and development tax credits	3,328	3,244
Allowances for accounts receivable	1,168	2,773
Deferred rent obligation	7,555	328
Stock compensation	25,264	18,270
Other accrued liabilities	2,223	2,171
Deferred revenue	17,797	17,754
Other	1,473	3,101
Total gross deferred tax assets	60,502	49,304
Valuation allowance	-3,420	-2,627
Total deferred tax assets	57,082	46,677
Deferred tax liabilities:
Intangible assets	-40,463	-49,555
Capitalized software development	-15,769	-8,641
Property and equipment	-4,621	-3,784
Investments	-14,913	0
Total deferred tax liabilities	-75,766	-61,980
Net deferred tax (liabilities) assets	($18,684)	($15,303)

INCOME_TAXES_Reconciliation_of

INCOME TAXES (Reconciliation of the Federal Statutory Income Tax Rate to Effective Income Tax Rate) (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Income tax computed at federal statutory tax rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	6.00%	-6.00%	5.00%
Research and development credits	86.00%	-98.00%	0.00%
Permanent differences	-87.00%	20.00%	6.00%
Valuation allowance	-21.00%	33.00%	0.00%
Total	19.00%	-16.00%	46.00%

INCOME_TAXES_Reconciliation_of1

INCOME TAXES (Reconciliation of Beginning and Ending Amount of Uncertain Tax Benefits) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning uncertain tax benefits	$4,851	$1,761	$1,685
Prior year – decreases	-79	-537	-140
Prior year – increases	887	501	177
Acquired balances	0	2,339	0
Current year - decreases	-212	0	0
Current year – increases	366	787	39
Ending uncertain tax benefits	$5,813	$4,851	$1,761

EMPLOYEE_BENEFIT_PLAN_Addition

EMPLOYEE BENEFIT PLAN (Additional Information) (Detail) (Defined Contribution Pension Plan, USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Discretionary Contributions by Employer	$4.50	$3.20	$2.40

QUARTERLY_FINANCIAL_INFORMATIO2

QUARTERLY FINANCIAL INFORMATION (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Business services	$201,072	$179,711	$175,949	$154,502	$162,529	$141,326	$137,919	$121,463	$711,234	$563,237	$408,496
Implementation and other	12,142	10,717	9,973	8,533	9,050	10,201	8,382	4,133	41,365	31,766	13,775
Total revenue	213,214	190,428	185,922	163,035	171,579	151,527	146,301	125,596	752,599	595,003	422,271
Expense:
Direct operating	76,274	79,343	74,774	72,148	62,852	63,245	59,390	53,185	302,539	238,672	166,886
Selling and marketing	50,533	45,206	50,722	43,227	37,947	37,584	41,035	32,922	189,688	149,488	104,300
Research and development	19,802	18,087	16,417	15,155	16,322	15,104	14,269	11,944	69,461	57,639	33,792
General and administrative	33,592	31,800	30,443	29,357	22,339	21,690	24,670	31,077	125,192	99,776	57,025
Depreciation and amortization	18,071	17,258	15,186	14,249	12,864	11,263	11,107	8,341	64,764	43,575	25,641
Total expense	198,272	191,694	187,542	174,136	152,324	148,886	150,471	137,469	751,644	589,150	387,644
Operating (loss) income	14,942	-1,266	-1,620	-11,101	19,255	2,641	-4,170	-11,873	955	5,853	34,627
Other (expense) income:
Interest expense	-911	-1,244	-1,275	-1,265	-1,319	-1,421	-1,001	-164	-4,695	-3,905	-407
Other income	27	26	-6	-171	136	30	63	54	-124	283	658
Total other (expense) income	-884	-1,218	-1,281	-1,436	-1,183	-1,391	-938	-110	-4,819	-3,622	251
(Loss) income before income tax benefit (provision)	14,058	-2,484	-2,901	-12,537	18,072	1,250	-5,108	-11,983	-3,864	2,231	34,878
Income tax benefit (provision)	-5,329	853	739	4,482	-4,927	-80	-7,313	12,683	745	363	-16,146
Net (loss) income	$8,729	($1,631)	($2,162)	($8,055)	$13,145	$1,170	($12,421)	$700	($3,119)	$2,594	$18,732
Net (loss) income per share - Basic (in dollars per share)	$0.23	($0.04)	($0.06)	($0.21)	$0.35	$0.03	($0.34)	$0.02	($0.08)	$0.07	$0.52
Net (loss) income per share - Diluted (in dollars per share)	$0.22	($0.04)	($0.06)	($0.21)	$0.34	$0.03	($0.34)	$0.02	($0.08)	$0.07	$0.50
Weighted average shares used in computing net (loss) income per share:
Basic (in shares)	38,097	37,999	37,860	37,484	37,262	36,970	36,760	36,409	37,862	36,856	35,956
Diluted (in shares)	39,040	37,999	37,860	37,484	38,645	38,343	36,760	37,744	37,862	38,257	37,133

SUBSEQUENT_EVENT_Details

SUBSEQUENT EVENT (Details) (Subsequent Event, USD $)	0 Months Ended
	Jan. 13, 2015	Jan. 23, 2015
RazorInsights
Subsequent Event [Line Items]
Cash payments	$40,000,000
weOMR
Subsequent Event [Line Items]
Cash payments		22,000,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		$18,000,000