CoStar (CSGP) 10-Q 30 Oct 14 2014 Q3 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 24, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'COSTAR GROUP INC	'
Entity Central Index Key	'0001057352	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	32,349,264

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]	'	'	'	'
Revenues	$153,056	$112,301	$419,840	$325,333
Cost of revenues	40,932	31,724	114,056	97,431
Gross margin	112,124	80,577	305,784	227,902
Operating expenses:	'	'	'	'
Selling and marketing	40,668	23,625	109,302	74,139
Software development	14,227	11,562	41,721	35,152
General and administrative	25,388	21,940	76,535	74,457
Purchase amortization	8,361	3,680	20,696	11,699
Total operating expenses	88,644	60,807	248,254	195,447
Income from operations	23,480	19,770	57,530	32,455
Interest and other income	46	52	245	239
Interest and other expense	-2,698	-1,736	-8,066	-5,249
Income before income taxes	20,828	18,086	49,709	27,445
Income tax expense, net	7,871	7,034	18,763	10,510
Net income	$12,957	$11,052	$30,946	$16,935
Net income per share-basic (in dollars per share)	$0.41	$0.40	$1.04	$0.61
Net income per share-diluted (in dollars per share)	$0.40	$0.39	$1.03	$0.60
Weighted average outstanding shares-basic (in shares)	31,742	27,758	29,692	27,607
Weighted average outstanding shares-diluted (in shares)	32,075	28,349	30,134	28,137

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income	$12,957	$11,052	$30,946	$16,935
Other comprehensive income (loss), net of tax	'	'	'	'
Foreign currency translation adjustment	-1,413	1,652	-452	20
Net decrease in unrealized loss on investments	42	0	241	63
Total other comprehensive income (loss)	-1,371	1,652	-211	83
Total comprehensive income	$11,586	$12,704	$30,735	$17,018

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$486,195	$255,953
Accounts receivable, less allowance for doubtful accounts of approximately $5,027 and $3,397 as of September 30, 2014 and December 31, 2013, respectively	39,051	20,761
Deferred and other income taxes, net	24,394	22,506
Prepaid expenses and other current assets	9,754	6,597
Debt issuance costs, net	3,358	2,649
Total current assets	562,752	308,466
Long-term investments	21,081	21,990
Property and equipment, net	70,675	57,719
Goodwill	1,139,917	718,587
Intangibles and other assets, net	257,177	144,472
Deposits and other assets	2,045	1,855
Debt issuance costs, net	10,694	3,893
Total assets	2,064,341	1,256,982
Current liabilities:	'	'
Current portion of long-term debt	20,000	24,063
Accounts payable	7,604	4,939
Accrued wages and commissions	21,656	20,104
Accrued expenses	30,107	23,200
Deferred gain on the sale of building	2,523	2,523
Income taxes payable	0	2,362
Deferred revenue	38,311	34,362
Total current liabilities	120,201	111,553
Long-term debt, less current portion	370,000	129,062
Deferred gain on the sale of building	24,393	26,286
Deferred rent	25,961	22,828
Deferred income taxes, net	26,532	34,582
Income taxes payable	4,881	4,809
Total liabilities	571,968	329,120
Stockholders' equity:	'	'
Total stockholders’ equity	1,492,373	927,862
Total liabilities and stockholders’ equity	$2,064,341	$1,256,982

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Allowance for doubtful accounts	$5,027	$3,397

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities:	'	'
Net income	$30,946,000	$16,935,000
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation	11,089,000	9,174,000
Amortization	39,644,000	21,063,000
Amortization of debt issuance costs	2,459,000	2,273,000
Impairment loss	1,799,000	0
Excess tax benefit from stock-based compensation	-28,167,000	-15,405,000
Stock-based compensation expense	20,906,000	32,270,000
Deferred income tax benefit, net	-1,236,000	-6,448,000
Provision for losses on accounts receivable	3,798,000	1,819,000
Changes in operating assets and liabilities, net of acquisitions:	'	'
Accounts receivable	-11,575,000	-8,305,000
Prepaid expenses and other current assets	-2,306,000	-533,000
Deposits and other assets	-68,000	220,000
Accounts payable and other liabilities	24,712,000	17,413,000
Deferred revenue	4,035,000	2,352,000
Net cash provided by operating activities	96,036,000	72,828,000
Investing activities:	'	'
Proceeds from sale and settlement of investments	1,150,000	87,000
Purchases of property and equipment and other assets	-20,865,000	-15,331,000
Acquisitions, net of cash acquired	584,218,000	0
Net cash used in investing activities	-603,933,000	-15,244,000
Financing activities:	'	'
Proceeds from long-term debt	550,000,000	0
Payments of long-term debt	-313,125,000	-13,125,000
Payments of debt issuance costs	-9,969,000	0
Payments of deferred consideration	-1,344,000	-1,344,000
Excess tax benefit from stock-based compensation	28,167,000	15,405,000
Repurchase of restricted stock to satisfy tax withholding obligations	-49,998,000	-7,563,000
Proceeds from equity offering, net of transaction costs	529,360,000	0
Proceeds from exercise of stock options and employee stock purchase plan	5,157,000	15,846,000
Net cash provided by financing activities	738,248,000	9,219,000
Effect of foreign currency exchange rates on cash and cash equivalents	-109,000	108,000
Net increase in cash and cash equivalents	230,242,000	66,911,000
Cash and cash equivalents at the beginning of period	255,953,000	156,027,000
Cash and cash equivalents at the end of period	$486,195,000	$222,938,000

ORGANIZATION

ORGANIZATION	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
ORGANIZATION	'
	ORGANIZATION
	CoStar Group, Inc. (the “Company” or “CoStar”) provides information, analytics and marketing services to the commercial real estate and related business community through its comprehensive, proprietary database of commercial real estate information covering the United States (“U.S.”), the United Kingdom (“U.K.”), Toronto, Canada, and parts of France, as well as its complementary online marketplaces for commercial real estate listings and apartment rentals. The Company operates within two operating segments, North America and International, and its services are typically distributed to its clients under subscription-based license agreements that renew automatically, a majority of which have a term of one year.

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	'
	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Basis of Presentation
	The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Accounting policies are consistent for each operating segment.
	Interim Financial Statements
	The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information. In the opinion of the Company’s management, the financial statements reflect all adjustments necessary to present fairly the Company’s financial position at September 30, 2014, the results of its operations for the three and nine months ended September 30, 2014 and 2013, its comprehensive income for the three and nine months ended September 30, 2014 and 2013, and its cash flows for the nine months ended September 30, 2014 and 2013. These adjustments are of a normal recurring nature.
	Certain notes and other information have been condensed or omitted from the interim financial statements presented in this Quarterly Report on Form 10-Q. Therefore, these financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2013.
	The results of operations for the three and nine months ended September 30, 2014 are not necessarily indicative of future financial results.
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
	Foreign Currency Translation
	The Company’s functional currency in its foreign locations is the local currency. Assets and liabilities are translated into U.S. dollars as of the balance sheet dates. Revenues, expenses, gains and losses are translated at the average exchange rates in effect during each period. Gains and losses resulting from translation are included in accumulated other comprehensive income (loss). Net gains or losses resulting from foreign currency exchange transactions are included in the condensed consolidated statements of operations. There were no material gains or losses from foreign currency exchange transactions for the three and nine months ended September 30, 2014 and 2013.
	2	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES — (CONTINUED)
	Accumulated Other Comprehensive Loss
	The components of accumulated other comprehensive loss were as follows (in thousands):
		September 30,				December 31,
		2014				2013
	Foreign currency translation adjustment	$	(4,455	)		$	(4,003	)
	Accumulated net unrealized loss on investments, net of tax	(1,286		)		(1,527		)
	Total accumulated other comprehensive loss	$	(5,741	)		$	(5,530	)
	There were no amounts reclassified out of accumulated other comprehensive loss to the condensed consolidated statements of operations for the three and nine months ended September 30, 2014 and 2013.
	Net Income Per Share
	Net income per share is computed by dividing net income by the weighted average number of common shares outstanding during the period on a basic and diluted basis. The Company’s potentially dilutive securities include stock options and restricted stock. Diluted net income per share considers the impact of potentially dilutive securities except in periods in which there is a net loss, as the inclusion of the potentially dilutive common shares would have an anti-dilutive effect.
	The following table sets forth the calculation of basic and diluted net income per share (in thousands, except per share data):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014		2013
	Numerator:
	Net income	$	12,957			$	11,052		$	30,946	$	16,935
	Denominator:
	Denominator for basic net income per share — weighted-average outstanding shares	31,742				27,758			29,692		27,607
	Effect of dilutive securities:
	Stock options and restricted stock	333				591			442		530
	Denominator for diluted net income per share — weighted-average outstanding shares	32,075				28,349			30,134		28,137
	Net income per share — basic	$	0.41			$	0.4		$	1.04	$	0.61
	Net income per share — diluted	$	0.4			$	0.39		$	1.03	$	0.6
	Employee stock options with exercise prices greater than the average market price of the Company’s common stock for the period are excluded from the calculation of diluted net income per share as their inclusion would be anti-dilutive. The following table summarizes the potential common shares excluded from the diluted calculation (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014		2013
	Employee stock options	80			—			80		—
	Additionally, shares of restricted common stock that vest based on Company performance conditions that have not been achieved as of the end of the period are not included in the computation of basic or diluted earnings per share.
	2	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES — (CONTINUED)
	Stock-Based Compensation
	Equity instruments issued in exchange for employee services are accounted for using a fair-value based method and the fair value of such equity instruments is recognized as expense in the condensed consolidated statements of operations.
	Stock-based compensation expense is measured at the grant date of the stock-based awards that vest over set time periods based on their fair values, and is recognized on a straight line basis as expense over the vesting periods of the awards, net of an estimated forfeiture rate. For equity instruments that vest based on performance, the Company assesses the probability of the achievement of the performance conditions at the end of each reporting period, or more frequently based upon the occurrence of events that may change the probability of whether the performance conditions would be met. If the Company's initial estimates of the achievement of the performance conditions change, the related stock-based compensation expense and timing of recognition may fluctuate from period to period based on those estimates. If the performance conditions are not met, no stock-based compensation expense will be recognized, and any previously recognized stock-based compensation expense will be reversed.
	In 2012, the Company granted performance-based restricted common stock awards that vest upon the Company's achievement of $90.0 million of cumulative net income before interest, income taxes, depreciation and amortization ("EBITDA") over a period of four consecutive calendar quarters if such performance is achieved by March 31, 2017, subject to certain approvals under the CoStar Group, Inc. 2007 Stock Incentive Plan. As of March 31, 2014, the Company had satisfied all performance and service conditions, and as a result, the restricted common stock granted under these awards vested. The Company recorded approximately $0 and $3.1 million of stock-based compensation expense related to the 2012 performance-based restricted common stock for the three months ended September 30, 2014 and 2013, respectively. The Company recorded approximately $2.2 million and $17.5 million of stock-based compensation expense related to the 2012 performance-based restricted common stock for the nine months ended September 30, 2014 and 2013, respectively.
	Cash flows resulting from excess tax benefits are classified as part of cash flows from operating and financing activities. Excess tax benefits represent tax benefits related to stock-based compensation in excess of the associated deferred tax asset for such equity compensation. Net cash proceeds from the exercise of stock options and the purchase of shares under the Employee Stock Purchase Plan (“ESPP”) were approximately $1.6 million and $6.9 million for the three months ended September 30, 2014 and 2013, respectively. Net cash proceeds from the exercise of stock options and the purchase of shares under the ESPP were approximately $5.2 million and $15.8 million for the nine months ended September 30, 2014 and 2013, respectively. The Company realized approximately $1.3 million and $5.7 million of excess tax benefits from stock options exercised and restricted stock awards vested for the three months ended September 30, 2014 and 2013, respectively and realized approximately $28.2 million and $15.4 million of excess tax benefits from stock options exercised and restricted stock awards vested for the nine months ended September 30, 2014 and 2013, respectively. The effect of the excess tax benefit as of September 30, 2014 was primarily recorded in deferred and other income taxes, net and additional paid-in capital included within total stockholders' equity in the condensed consolidated balance sheets. The effect of the excess tax benefit as of December 31, 2013 was recorded in current income taxes payable and additional paid-in capital included within total stockholders' equity in the condensed consolidated balance sheets.
	Stock-based compensation expense for stock options and restricted stock issued under equity incentive plans and stock purchases under the ESPP included in the Company’s results of operations were as follows (in thousands):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014		2013
	Cost of revenues	$	1,067			$	1,061		$	3,331	$	3,353
	Selling and marketing	954				944			2,729		3,763
	Software development	1,179				1,608			3,867		5,439
	General and administrative	3,447				4,175			10,979		19,715
	Total stock-based compensation	$	6,647			$	7,788		$	20,906	$	32,270
	Options to purchase 20,366 and 150,560 shares were exercised during the three months ended September 30, 2014 and 2013, respectively. Options to purchase 66,201 and 340,599 shares were exercised during the nine months ended September 30, 2014 and 2013, respectively.
	2	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES — (CONTINUED)
	Capitalized Product Development Costs
	Product development costs are expensed as incurred until technological feasibility has been established, at which time such costs are capitalized. Costs are capitalized, to the extent that the capitalizable costs do not exceed the realizable value of such costs, until the product is available for general release to customers. The Company defines the establishment of technological feasibility as the completion of all planning, designing, coding and testing activities that are necessary to establish products that meet design specifications including functions, features and technical performance requirements. The Company's capitalized product development costs had a total net book value of approximately $0 and $111,000 as of September 30, 2014 and December 31, 2013, respectively. These capitalized product development costs are included in intangible and other assets in the Company’s condensed consolidated balance sheets. Amortization is computed using a straight-line method over the remaining estimated economic life of the product, typically three to five years after the software is ready for its intended use. The Company amortized capitalized product development costs of approximately $16,000 and $48,000 for the three months ended September 30, 2014 and 2013, respectively. The Company amortized capitalized product development costs of approximately $111,000 and $143,000 for the nine months ended September 30, 2014 and 2013, respectively.
	Debt Issuance Costs
	Costs incurred in connection with the issuance of long-term debt are capitalized and amortized as interest expense over the term of the related debt using the effective interest method. Upon a refinancing, previously capitalized debt issuance costs are expensed and included in loss on extinguishment of debt if the Company determines that there has been a substantial modification of the related debt. If the Company determines that there has not been a substantial modification of the related debt, any previously capitalized debt issuance costs are amortized as interest expense over the term of the new debt instrument using the effective interest method. The Company had capitalized debt issuance costs of approximately $14.1 million and $6.5 million as of September 30, 2014 and December 31, 2013, respectively. The debt issuance costs are associated with the financing commitment received from JPMorgan Chase Bank, N.A. (“J.P. Morgan Bank”) on April 27, 2011, the subsequent term loan facility and revolving credit facility established under a credit agreement dated February 16, 2012 (the “2012 Credit Agreement”), the financing commitment received from J.P. Morgan Bank, Bank of America, N.A., SunTrust Bank and Wells Fargo Bank, National Association on February 28, 2014, and the subsequent term loan facility and revolving credit facility established under a credit agreement dated April 1, 2014 (the “2014 Credit Agreement”). See Note 8 for additional information regarding the term loan facility and revolving credit facility. The Company amortized debt issuance costs of approximately $904,000 and $760,000 for the three months ended September 30, 2014 and 2013, respectively. The Company amortized debt issuance costs of approximately $2.5 million and $2.3 million for the nine months ended September 30, 2014 and 2013, respectively.
	Recent Accounting Pronouncements
There have been no developments to the Recent Accounting Pronouncements discussion included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013, including the expected dates of adoption and estimated effects on the Company’s condensed consolidated financial statements, except for the following:
In May 2014, the Financial Accounting Standards Board (“FASB”) and International Accounting Standards Board (“IASB”) jointly issued a new revenue recognition standard that will improve financial reporting by creating common recognition guidance for U.S. GAAP and International Financial Reporting Standards (“IFRS”). This guidance removes inconsistencies and weaknesses in revenue requirements, provides a more robust framework for addressing revenue issues, improves the comparability of revenue recognition practices across industries, provides more useful information to users of financial statements through improved disclosure requirements and simplifies the presentation of financial statements. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance is effective on a retrospective basis for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. Early application is not permitted. The Company is evaluating the impact this guidance will have on its financial statements.

ACQUISITION

ACQUISITION	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
ACQUISITION	'
	ACQUISITION
	On February 28, 2014, the Company and Classified Ventures, LLC (“CV”) entered into an Asset Purchase Agreement (the “Asset Purchase Agreement”). Pursuant to the Asset Purchase Agreement, on April 1, 2014 (the “Closing Date”), the Company purchased from CV certain assets and assumed certain liabilities, in each case, related to the Apartments.com business (collectively, the “Apartments.com Business”). Apartments.com is a national online apartment rentals resource for renters, property managers and owners. Apartments.com offers renters a database of apartment listings and provides professional property management companies and landlords with an advertising destination. Renters can conduct personalized searches of apartment listings and view video demonstrations and community reviews through the Apartments.com website and mobile applications. The Apartments.com network of rental websites also includes ApartmentHomeLiving.com, another national online apartment rentals resource. The acquisition increased the Company's presence in the multifamily vertical.
	In consideration for the purchase of the Apartments.com Business, on April 1, 2014, the Company paid $587.1 million in cash, including an estimated $2.1 million in connection with a preliminary net working capital adjustment as of the Closing Date. Pursuant to the terms of the Asset Purchase Agreement, the purchase price was reduced by approximately $2.9 million following the final determination of the net working capital of the Apartments.com Business as of the Closing Date, and CV paid the Company $2.9 million on July 9, 2014.
	The Company applied the acquisition method to account for the Apartments.com transaction, which requires that, among other things, assets acquired and liabilities assumed be recorded at their fair values as of the acquisition date. The following table summarizes the amounts for acquired assets and liabilities recorded at their fair values as of the acquisition date (in thousands):
	Accounts receivable	$	11,402
	Goodwill	421,724
	Acquired trade names and other	71,779
	Acquired customer base	69,684
	Acquired database technology	11,489
	Acquired building photography	1,006
	Other assets and liabilities	(2,866		)
	Fair value of identifiable net assets acquired	$	584,218
	The net assets of Apartments.com were recorded at their estimated fair value. In valuing acquired assets and liabilities, fair value estimates are based on, but are not limited to, future expected cash flows, market rate assumptions for contractual obligations, and appropriate discount rates.
	The acquired customer base for the acquisition consists of one distinct intangible asset, is composed of acquired customer contracts and the related customer relationships, and has an estimated useful life of 10 years. The acquired database technology has an estimated useful life of 1 year due to the Company's intent to replace the existing database technology in 2015. The acquired trade names and other intangible assets have a weighted average estimated useful life of 13 years. The acquired building photography has an estimated useful life of 3 years. Amortization of the acquired customer base is recognized on an accelerated basis related to the expected economic benefit of the intangible asset, while amortization of the acquired database technology, acquired building photography and acquired trade names and other are recognized on a straight-line basis over the estimated useful life. Goodwill recorded in connection with this acquisition is not amortized, but is subject to annual impairment tests. The $421.7 million of goodwill recorded as part of the acquisition is associated with the Company's North America operating segment and the entire amount of goodwill is expected to be deductible for income tax purposes in future periods. The purchase accounting described above is preliminary and is subject to change.
	Goodwill is calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. Specifically, the goodwill recorded as part of the Apartments.com acquisition includes: (i) the expected synergies and other benefits that the Company believes will result from combining its operations with Apartments.com's operations; and (ii) any intangible assets that do not qualify for separate recognition, such as the assembled workforce.
	3	ACQUISITIONS — (CONTINUED)
	The Company's consolidated revenue for the three and nine months ended September 30, 2014, included $26.0 million and $51.1 million from the Apartments.com Business, respectively. The Company's consolidated income before income taxes for the three and nine months ended September 30, 2014, included a $7.5 million and $15.7 million loss before income taxes from the Apartments.com Business, respectively. The Company's consolidated revenue and income before income taxes for the three and nine months ended September 30, 2013 did not include any amount from the Apartments.com Business.
	The following unaudited pro forma amounts present consolidated information as if the acquisition had been completed as of January 1, 2013 (in thousands except per share data):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2014			2013		2014		2013
	Revenue	$	153,056		$	134,328	$	442,244	$	389,059
	Net income	$	16,044		$	7,439	$	34,694	$	5,381
	Net income per share — basic	$	0.51		$	0.27	$	1.17	$	0.19
	Net income per share — diluted	$	0.5		$	0.26	$	1.15	$	0.19
	This information is based on historical results of operations, adjusted for the allocation of purchase price and other acquisition accounting adjustments, including: (i) the amortization associated with the acquired intangible assets; (ii) interest expense associated with debt used to fund a portion of the acquisition; and (iii) income tax expense associated with pro forma adjustments and the historical results of Apartments.com calculated at a tax rate of 38%. The unaudited pro forma results do not include: (i) any potential synergies, cost savings or other expected benefits of the acquisition and (ii) the non-recurring acquisition costs incurred through the date of acquisition. Accordingly, the unaudited pro forma amounts are for comparative purposes only and may not necessarily reflect the results of operations which would have resulted had the acquisition been completed at the beginning of the applicable period and may not be indicative of the results that will be attained in the future.
	As a result of the acquisition of the Apartments.com Business, the Company recorded approximately $1.4 million in acquisition-related costs for the nine months ended September 30, 2014. The Company did not record any acquisition-related costs for the three months ended September 30, 2014 or the three and nine months ended September 30, 2013. These costs include expenses directly related to acquiring the Apartments.com Business, are expensed as incurred and are recorded in general and administrative expense.

INVESTMENTS

INVESTMENTS	9 Months Ended
	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
INVESTMENTS	'
	INVESTMENTS
	The Company determines the appropriate classification of debt and equity investments at the time of purchase and re-evaluates such designation as of each balance sheet date. The Company considers all of its investments to be available-for-sale. The Company's investments consist of long-term variable rate debt instruments with an auction reset feature, referred to as auction rate securities (“ARS”). Investments are carried at fair market value.
	Scheduled maturities of investments classified as available-for-sale as of September 30, 2014 are as follows (in thousands):
	Maturity		Fair Value
	Due:
	October 1, 2014 — September 30, 2015		$	—
	October 1, 2015 — September 30, 2019		816
	October 1, 2019 — September 30, 2024		—
	After September 30, 2024		20,265
	Available-for-sale investments		$	21,081
	4	INVESTMENTS — (CONTINUED)
	The Company had no realized gains on its investments for each of the three and nine months ended September 30, 2014 and 2013. The Company had no realized losses on its investments for each of the three and nine months ended September 30, 2014 and 2013. Realized gains and losses from the sale of available-for-sale securities are determined on a specific-identification basis.
	Changes in unrealized holding gains and losses, net of the related tax effect, on available-for-sale securities are excluded from earnings and are reported as a separate component of accumulated other comprehensive income (loss) in stockholders’ equity until realized. A decline in market value of any available-for-sale security below cost that is deemed to be other-than-temporary results in a reduction in carrying amount to fair value. The impairment is charged to earnings and a new cost basis for the security is established. Dividend and interest income are recognized when earned.
	As of September 30, 2014, the amortized cost basis and fair value of investments classified as available-for-sale were as follows (in thousands):
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Gains			Losses
	Auction rate securities	$	22,367		$	374		$	(1,660	)	$	21,081
	Available-for-sale investments	$	22,367		$	374		$	(1,660	)	$	21,081
	As of December 31, 2013, the amortized cost basis and fair value of investments classified as available-for-sale were as follows (in thousands):
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Gains			Losses
	Auction rate securities	$	23,517		$	411		$	(1,938	)	$	21,990
	Available-for-sale investments	$	23,517		$	411		$	(1,938	)	$	21,990
	The unrealized losses on the Company’s investments as of September 30, 2014 and December 31, 2013 were generated primarily from changes in interest rates and ARS that failed to settle at auction, due to adverse conditions in the global credit markets. The losses are considered temporary, as the contractual terms of these investments do not permit the issuer to settle the security at a price less than the amortized cost of the investment. Because the Company does not intend to sell these instruments and it is more likely than not that the Company will not be required to sell these instruments prior to anticipated recovery, which may be at maturity, the Company does not consider these investments to be other-than-temporarily impaired as of September 30, 2014 and December 31, 2013. See Note 5 for further discussion of the fair value of the Company’s financial assets.
	The components of the Company’s investments in an unrealized loss position for twelve months or longer were as follows (in thousands):
		September 30,						December 31,
		2014						2013
		Aggregate			Gross			Aggregate			Gross
		Fair			Unrealized			Fair			Unrealized
		Value			Losses			Value			Losses
	Auction rate securities	$	20,265		$	(1,660	)	$	21,137		$	(1,938	)
	Investments in an unrealized loss position	$	20,265		$	(1,660	)	$	21,137		$	(1,938	)
	The Company did not have any investments in an unrealized loss position for less than twelve months as of September 30, 2014 and December 31, 2013, respectively.

FAIR_VALUE

FAIR VALUE	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
FAIR VALUE	'
	FAIR VALUE
	Fair value is defined as the price that would be received in the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. There is a three-tier fair value hierarchy, which categorizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs for which little or no market data exists, therefore requiring an entity to develop its own assumptions.
	The following table represents the Company's fair value hierarchy for its financial assets (cash, cash equivalents and investments) measured at fair value on a recurring basis as of September 30, 2014 (in thousands):
		Level 1			Level 2		Level 3			Total
	Assets:
	Cash	$	482,728		$	—	$	—		$	482,728
	Money market funds	655			—		—			655
	Commercial paper	2,812			—		—			2,812
	Auction rate securities	—			—		21,081			21,081
	Total assets measured at fair value	$	486,195		$	—	$	21,081		$	507,276
	The following table represents the Company's fair value hierarchy for its financial assets (cash, cash equivalents and investments) and liabilities measured at fair value on a recurring basis as of December 31, 2013 (in thousands):
		Level 1			Level 2		Level 3			Total
	Assets:
	Cash	$	134,989		$	—	$	—		$	134,989
	Money market funds	50,593			—		—			50,593
	Commercial paper	70,371			—		—			70,371
	Auction rate securities	—			—		21,990			21,990
	Total assets measured at fair value	$	255,953		$	—	$	21,990		$	277,943
	Liabilities:
	Deferred consideration	$	—		$	—	$	1,344		$	1,344
	Total liabilities measured at fair value	$	—		$	—	$	1,344		$	1,344
	The Company’s Level 3 assets consist of ARS, whose underlying assets are primarily student loan securities supported by guarantees from the Federal Family Education Loan Program (“FFELP”) of the U.S. Department of Education.
	The following tables summarize changes in fair value of the Company’s Level 3 assets for the three and nine months ended September 30, 2014 and 2013 (in thousands):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2014			2013		2014			2013
	Balance at beginning of period	$	21,639		$	21,675	$	21,990		$	21,662
	Decrease in unrealized loss included in accumulated other comprehensive loss	42			—		241			63
	Settlements	(600		)	—		(1,150		)	(50		)
	Balance at end of period	$	21,081		$	21,675	$	21,081		$	21,675
	5	FAIR VALUE — (CONTINUED)
	The following table summarizes changes in fair value of the Company’s Level 3 assets from December 31, 2007 to September 30, 2014 (in thousands):
		Auction
		Rate
		Securities
	Balance at December 31, 2007	$	53,975
	Increase in unrealized loss included in accumulated other comprehensive loss	(3,710		)
	Settlements	(20,925		)
	Balance at December 31, 2008	29,340
	Decrease in unrealized loss included in accumulated other comprehensive loss	684
	Settlements	(300		)
	Balance at December 31, 2009	29,724
	Decrease in unrealized loss included in accumulated other comprehensive loss	40
	Settlements	(575		)
	Balance at December 31, 2010	29,189
	Decrease in unrealized loss included in accumulated other comprehensive loss	245
	Settlements	(4,850		)
	Balance at December 31, 2011	24,584
	Auction rate securities upon acquisition	442
	Decrease in unrealized loss included in accumulated other comprehensive loss	836
	Settlements	(4,200		)
	Balance at December 31, 2012	21,662
	Decrease in unrealized loss included in accumulated other comprehensive loss	378
	Settlements	(50		)
	Balance at December 31, 2013	21,990
	Decrease in unrealized loss included in accumulated other comprehensive loss	241
	Settlements	(1,150		)
	Balance at September 30, 2014	$	21,081
	ARS are variable rate debt instruments whose interest rates are reset approximately every 28 days. The majority of the underlying securities have contractual maturities greater than twenty years. The ARS are recorded at fair value.
	As of September 30, 2014, the Company held ARS with $23.2 million par value, all of which failed to settle at auction. The majority of these investments are of high credit quality with AAA credit ratings and are primarily student loan securities supported by guarantees from the FFELP of the U.S. Department of Education. The Company may not be able to liquidate and fully recover the carrying value of the ARS in the near term. As a result, these securities are classified as long-term investments in the Company’s condensed consolidated balance sheet as of September 30, 2014.
	While the Company continues to earn interest on its ARS investments at the contractual rate, these investments are not currently actively trading and therefore do not currently have a readily determinable market value. The estimated fair value of the ARS no longer approximates par value. The Company used a discounted cash flow model to determine the estimated fair value of its investment in ARS as of September 30, 2014. The assumptions used in preparing the discounted cash flow model include estimates for interest rates, credit spreads, timing and amount of contractual cash flows, liquidity risk premiums, expected holding periods and default risk. The Company updates the discounted cash flow model on a quarterly basis to reflect any changes in the assumptions used in the model and settlements of ARS investments that occurred during the period.
	5	FAIR VALUE — (CONTINUED)
	The only significant unobservable input in the discounted cash flow model is the discount rate. The discount rate used represents the Company's estimate of the yield expected by a market participant from the ARS investments. The weighted average discount rate used in the discounted cash flow model as of September 30, 2014 and December 31, 2013 was approximately 5.1% and 4.9%, respectively. Selecting another discount rate within the range used in the discounted cash flow model would not result in a significant change to the fair value of the ARS.
Based on this assessment of fair value, as of September 30, 2014, the Company determined there was a decline in the fair value of its ARS investments of approximately $1.3 million. The decline was deemed to be a temporary impairment and recorded as an unrealized loss in accumulated other comprehensive loss in stockholders’ equity. In addition, while a majority of the ARS are currently rated AAA, if the issuers are unable to successfully close future auctions and/or their credit ratings deteriorate, the Company may be required to record additional unrealized losses in accumulated other comprehensive loss or an other-than-temporary impairment charge to earnings on these investments.
As of September 30, 2014, the Company had no Level 3 liabilities. As of September 30, 2013, the Company held Level 3 liabilities for deferred consideration that it acquired as a result of the April 30, 2012 acquisition of LoopNet. The deferred consideration included potential deferred cash payments in connection with acquisitions LoopNet completed in 2010 including: (i) potential deferred cash payments due to the sellers of LandsofAmerica.com, LLC ("LandsofAmerica") on March 31, 2014 based on LandsofAmerica's achievement of financial and operational milestones, resulting in undiscounted deferred consideration as of December 31, 2013 of approximately $1.0 million; and (ii) potential deferred cash payments due to the sellers of Reaction Corp. ("Reaction Web") on March 31, 2014 based on Reaction Web's achievement of revenue milestones, resulting in undiscounted deferred consideration as of December 31, 2013 of approximately $344,000. On March 28, 2013, the Company paid $1.0 million to the sellers of LandsofAmerica for the achievement of financial and operational milestones in 2012 and paid approximately $344,000 to the sellers of Reaction Web for the achievement of revenue milestones in 2012. On March 31, 2014, the Company paid $1.0 million to the sellers of LandsofAmerica for the achievement of financial and operational milestones in 2013 and paid approximately $344,000 to the sellers of Reaction Web for the achievement of revenue milestones in 2013.
The following tables summarize changes in fair value of the Company’s Level 3 liabilities for the three and nine months ended September 30, 2014 and 2013 (in thousands):
	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2014			2013		2014			2013
Balance at beginning of period	$	—		$	1,146	$	1,344		$	2,304
Accretion for period	—			62		—			248
Payments made during period	—			—		(1,344		)	(1,344		)
Balance at end of period	$	—		$	1,208	$	—		$	1,208
The following table summarizes changes in fair value of the Company’s Level 3 liabilities from December 31, 2012 to September 30, 2014 (in thousands):
	Deferred
	Consideration
Balance at December 31, 2012	$	2,304
Accretion for 2013	384
Payments made in 2013	(1,344		)
Balance at December 31, 2013	1,344
Payments made from January 1, 2014 – September 30, 2014	(1,344		)
Balance at September 30, 2014	$	—
5	FAIR VALUE — (CONTINUED)
Prior to December 31, 2013, the Company used a discounted cash flow model to determine the estimated fair value of its Level 3 liabilities. The assumptions used in preparing the discounted cash flow model included the discount rate and probabilities for completion of financial and operational milestones. The only significant unobservable input in the discounted cash flow model used to determine the estimated fair value of the Company's Level 3 liabilities was the discount rate. The discount rate used represented LoopNet's cost of equity at the time of each acquisition plus a margin for counterparty risk. As of December 31, 2013, the Company recorded a liability for the entire amount of undiscounted deferred consideration paid on March 31, 2014.
Concentration of Credit Risk and Financial Instruments
The Company performs ongoing credit evaluations of its customers’ financial condition and generally does not require that its customers’ obligations to the Company be secured. The Company maintains reserves for estimated inherent credit losses, and such losses have been within management’s expectations. The large size and widespread nature of the Company’s customer base and the Company’s lack of dependence on any individual customer mitigates the risk of nonpayment of the Company’s accounts receivable. The carrying amount of the accounts receivable approximates the net realizable value. The carrying value of accounts receivable, accounts payable, accrued expenses, and long-term debt approximates fair value.

GOODWILL

GOODWILL	9 Months Ended
	Sep. 30, 2014
Goodwill [Abstract]	'
GOODWILL	'
	GOODWILL
	The changes in the carrying amount of goodwill by operating segment consist of the following (in thousands):
		North America		International			Total
	Goodwill, December 31, 2012	$	692,639	$	25,439		$	718,078
	Effect of foreign currency translation	—		509			509
	Goodwill, December 31, 2013	692,639		25,948			718,587
	Acquisition	421,724		—			421,724
	Effect of foreign currency translation	—		(394		)	(394		)
	Goodwill, September 30, 2014	$	1,114,363	$	25,554		$	1,139,917
	The Company recorded goodwill of approximately $421.7 million in connection with the April 1, 2014 acquisition of the Apartments.com Business.

INTANGIBLES_AND_OTHER_ASSETS

INTANGIBLES AND OTHER ASSETS	9 Months Ended
	Sep. 30, 2014
Intangibles and Other Assets [Abstract]	'
INTANGIBLES AND OTHER ASSETS	'
	INTANGIBLES AND OTHER ASSETS
	Intangibles and other assets consist of the following (in thousands, except amortization period data):
		September 30,			December 31,			Weighted-
		2014			2013			Average
								Amortization
								Period (in years)
	Capitalized product development cost	$	2,140		$	2,140		4
	Accumulated amortization	(2,140		)	(2,029		)
	Capitalized product development cost, net	—			111
	Building photography	14,918			13,743			5
	Accumulated amortization	(12,533		)	(12,005		)
	Building photography, net	2,385			1,738
	Acquired database technology	88,826			77,368			4
	Accumulated amortization	(54,981		)	(41,073		)
	Acquired database technology, net	33,845			36,295
	Acquired customer base	200,430			130,960			10
	Accumulated amortization	(95,264		)	(74,734		)
	Acquired customer base, net	105,166			56,226
	Acquired trade names and other (1)	128,349			59,336			13
	Accumulated amortization	(12,568		)	(9,234		)
	Acquired trade names and other, net	115,781			50,102
	Intangibles and other assets, net	$	257,177		$	144,472
	(1) The weighted-average amortization period for acquired trade names excludes $48.7 million for acquired trade names recorded in connection with the LoopNet acquisition on April 30, 2012, which amount is not amortized, but is subject to annual impairment tests.
	During the first quarter of 2014, the Company finalized a branding initiative plan that included, among other things, re-branding some of the services provided by its wholly owned subsidiaries, in order to better organize, update, streamline and optimize the Company’s branding strategy. The Company launched the branding initiative externally in the second quarter of 2014. Following the external launch of the branding initiative, the Company ceased using certain of its trade names. The Company evaluated these assets for impairment during the first quarter of 2014 and determined that the carrying value of trade names that the Company ceased using exceeded the fair value. The Company recorded an impairment charge of approximately $1.1 million in cost of revenues in the condensed consolidated statements of operations within the Company's North America operating segment for the three months ended March 31, 2014. The adjusted carrying value of the Company's trade name intangible assets associated with the branding initiative was amortized through the date of the external launch of the branding initiative and the fully amortized gross carrying amount was written off during the three months ended June 30, 2014.
	During the third quarter of 2014, the Company finalized and launched a separate marketing plan that included the re-branding of a service provided by another one of its wholly owned subsidiaries, in order to provide its customers with a more enhanced experience. Following the external launch of the marketing plan, the Company ceased using one of its trade names. The Company evaluated the asset for impairment during the third quarter of 2014 and determined that the carrying value of the trade name that the Company ceased using exceeded the fair value. The Company recorded an impairment charge of approximately $746,000 in cost of revenues in the condensed consolidated statements of operations within the Company's North America operating segment for the three months ended September 30, 2014.

LONGTERM_DEBT

LONG-TERM DEBT	9 Months Ended
	Sep. 30, 2014
Long-term Debt, Current and Noncurrent [Abstract]	'
LONG-TERM DEBT	'
	LONG-TERM DEBT
	On April 1, 2014 (the “Closing Date”), the Company entered into the 2014 Credit Agreement by and among the Company, as Borrower, CoStar Realty Information, Inc., as Co-Borrower, the Lenders from time to time party thereto and JPMorgan Chase Bank, N.A., as Administrative Agent. The 2014 Credit Agreement provides for a $400.0 million term loan facility and a $225.0 million revolving credit facility, each with a term of five years. The proceeds of the term loan facility and the initial borrowing of $150.0 million under the revolving credit facility on the Closing Date were used to refinance the 2012 Credit Agreement, including related fees and expenses, and to pay a portion of the consideration and transaction costs related to the acquisition of the Apartments.com Business. The undrawn proceeds of the revolving credit facility are available for the Company's working capital needs and other general corporate purposes. During June 2014, the Company repaid the $150.0 million initial borrowing under the revolving credit facility. The carrying value of the term loan facility approximates fair value and can be estimated through Level 3 unobservable inputs using an expected present value technique based on expected cash flows discounted using the current credit-adjusted risk-free rate, which approximates the rate of interest on the term loan facility at the origination.
	Effective April 1, 2014, the Company terminated the 2012 Credit Agreement and repaid all amounts outstanding thereunder, which amounts totaled $148.8 million. The Company evaluated the debt modification and determined that the modification did not qualify as an extinguishment of debt because the change in the present value of future cash flows between the initial term loan facility under the 2012 Credit Agreement and the new term loan facility under the 2014 Credit Agreement was not considered a substantial modification.
	The revolving credit facility includes a subfacility for swingline loans of up to $10.0 million, and up to $10.0 million of the revolving credit facility is available for the issuance of letters of credit. The term loan facility will amortize in quarterly installments in amounts resulting in an annual amortization of 5% during each of the first, second and third years, 10% during the fourth year and 15% during the fifth year after the Closing Date, with the remainder payable at final maturity. The loans under the 2014 Credit Agreement bear interest, at the Company's option, either (i) during any interest period selected by the Company, at the London interbank offered rate for deposits in U.S. dollars with a maturity comparable to such interest period, adjusted for statutory reserves (“LIBOR”), plus an initial spread of 2.00% per annum, subject to adjustment based on the First Lien Secured Leverage Ratio (as defined in the 2014 Credit Agreement) of the Company, or (ii) at the greatest of (x) the prime rate from time to time announced by JPMorgan Chase Bank, N.A., (y) the federal funds effective rate plus ½ of 1% and (z) LIBOR for a one-month interest period plus 1.00%, plus an initial spread of 1.00% per annum, subject to adjustment based on the First Lien Secured Leverage Ratio of the Company. If an event of default occurs under the 2014 Credit Agreement, the interest rate on overdue amounts will increase by 2.00% per annum. The obligations under the 2014 Credit Agreement are guaranteed by all material subsidiaries of the Company and are secured by a lien on substantially all of the assets of the Company and those of its material subsidiaries, in each case subject to certain exceptions, pursuant to security and guarantee documents entered into on the Closing Date.
	The 2014 Credit Agreement requires the Company to maintain (i) a First Lien Secured Leverage Ratio (as defined in the 2014 Credit Agreement) not exceeding 4.00 to 1.00 during each full fiscal quarter after the Closing Date through the three months ended March 31, 2016, and 3.50 to 1.00 thereafter and (ii) after the incurrence of additional indebtedness under certain specified exceptions in the 2014 Credit Agreement, a Total Leverage Ratio (as defined in the 2014 Credit Agreement) not exceeding 5.00 to 1.00 during each full fiscal quarter after the Closing Date through the three months ended March 31, 2016, and 4.50 to 1.00 thereafter. The 2014 Credit Agreement also includes other covenants, including covenants that, subject to certain exceptions, restrict the ability of the Company and its subsidiaries to (i) incur additional indebtedness, (ii) create, incur, assume or permit to exist any liens, (iii) enter into mergers, consolidations or similar transactions, (iv) make investments and acquisitions, (v) make certain dispositions of assets, (vi) make dividends, distributions and prepayments of certain indebtedness, and (vii) enter into certain transactions with affiliates. The Company was in compliance with the covenants in the 2014 Credit Agreement as of September 30, 2014.
	In connection with obtaining the term loan facility and revolving credit facility pursuant to the 2014 Credit Agreement, the Company incurred approximately $10.1 million in debt issuance costs as of April 1, 2014. The debt issuance costs were comprised of approximately $9.7 million in underwriting fees and approximately $400,000 primarily related to legal fees associated with the debt issuance. Approximately $10.0 million of the fees associated with the refinancing, along with the unamortized debt issuance cost from the 2012 Credit Agreement, are capitalized and amortized as interest expense over the term of the 2014 Credit Agreement using the effective interest method.
	8	LONG-TERM DEBT — (CONTINUED)
	As of September 30, 2014 and December 31, 2013, no amounts were outstanding under the revolving credit facilities. Total interest expense for the term loan facilities and revolving credit facilities was approximately $2.7 million and $1.7 million for the three months ended September 30, 2014 and 2013, respectively. Total interest expense for the term loan facilities and revolving credit facilities was approximately $8.1 million and $5.2 million for the nine months ended September 30, 2014 and 2013, respectively. Interest expense included amortized debt issuance costs of approximately $904,000 and $760,000 for the three months ended September 30, 2014 and 2013, respectively. Interest expense included amortized debt issuance costs of approximately $2.5 million and $2.3 million for the nine months ended September 30, 2014 and 2013, respectively. Total interest paid for the term loan facilities was approximately $1.7 million and $1.3 million for the three months ended September 30, 2014 and 2013, respectively. Total interest paid for the term loan facilities was approximately $5.4 million and $3.3 million for the nine months ended September 30, 2014 and 2013, respectively.

INCOME_TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
INCOME TAXES	'
	INCOME TAXES
	The income tax provision for each of the nine months ended September 30, 2014 and 2013 reflects an effective tax rate of approximately 38%.
	The Company is subject to taxation in the U.S. and various states and foreign jurisdictions. During September 2014, the statute of limitations expired for the Company's tax returns for tax year 2010. At the time of the expiration, no adjustments had been proposed by the Internal Revenue Service (“IRS”).
	During July 2014, the IRS completed its audit of the tax returns filed by LoopNet, the Company's subsidiary, for tax years 2009, 2010, 2011 and the four months ended April 30, 2012. No adjustments were made to the financial statements as a result of the completion of the IRS audit.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
COMMITMENTS AND CONTINGENCIES	'
	COMMITMENTS AND CONTINGENCIES
	The Company leases office facilities and office equipment under various non-cancelable operating leases. The leases contain various renewal options.
	On April 1, 2014, the Company entered into the 2014 Credit Agreement. The 2014 Credit Agreement provides for a $400.0 million term loan facility and a $225.0 million revolving credit facility, each with a term of five years. See Note 8 for additional information regarding the term loan facility and revolving credit facility.
	In May 2011, LoopNet, the Board of Directors of LoopNet (“the LoopNet Board”) and/or the Company were named as defendants in three purported class action lawsuits brought by alleged LoopNet stockholders challenging LoopNet's then-proposed merger with the Company. The stockholder actions alleged, among other things, that (i) each member of the LoopNet Board breached his fiduciary duties to LoopNet and its stockholders in authorizing the sale of LoopNet to the Company, (ii) the merger did not maximize value to LoopNet stockholders, (iii) LoopNet and the Company made incomplete or materially misleading disclosures about the transaction and (iv) LoopNet and the Company aided and abetted the breaches of fiduciary duty allegedly committed by the members of the LoopNet Board. The stockholder actions sought class action certification and equitable relief, including an injunction against consummation of the merger. The parties stipulated to the consolidation of the actions and permitted the filing of a consolidated complaint. In June 2011, counsel for the parties entered into a memorandum of understanding in which they agreed on the terms of a settlement of this litigation, which could result in a loss to the Company of approximately $200,000. On March 20, 2013, the California Superior Court declined to grant preliminary approval to the proposed settlement and issued an order scheduling a hearing on June 11, 2013 to show good cause why the case should not be dismissed. Shortly before the hearing, the plaintiffs filed a third supplemental submission in support of their motion for preliminary approval of the proposed settlement. The show cause hearing took place on May 13, 2014 and a follow up hearing took place on July 16, 2014. At the July 16, 2014 hearing the Court again denied preliminary approval of the settlement and encouraged the parties to discuss a potential disposition of the case due to the mootness of plaintiffs’ disclosure claims. The parties engaged in such discussions, and on October 14, 2014, the plaintiffs requested that the Court dismiss their claims with prejudice.  Upon entry of the dismissal, the Company (and its insurer) have agreed to reimburse certain legal fees to plaintiffs’ counsel, of which the Company will be responsible for approximately $200,000.
	10	COMMITMENTS AND CONTINGENCIES — (CONTINUED)
	On January 3, 2012, LoopNet, the Company’s wholly owned subsidiary, was sued by CIVIX-DDI, LLC (“Civix”) in the U.S. District Court for the Eastern District of Virginia for alleged infringement of U.S. Patent Nos. 6,385,622 and 6,415,291. The complaint seeks unspecified damages, attorneys' fees and costs. On February 16, 2012, LoopNet filed an answer to Civix’s complaint and filed counterclaims against Civix seeking, among other things, declaratory relief that the asserted patents are invalid, not infringed, and that Civix committed inequitable conduct during the prosecution and re-examination of the asserted patents. On or about May 14, 2012, Civix filed a motion for leave to amend its complaint against LoopNet in the U.S. District Court for the Eastern District of Virginia seeking to add the Company as a defendant, alleging that the Company's products also infringe Civix’s patents. The Company filed a motion opposing Civix’s motion, and on June 21, 2012, the district court denied Civix's motion to amend its complaint. On June 21, 2012, the Company filed an action in the U.S. District Court for the Northern District of Illinois seeking a declaratory judgment of non-infringement and invalidity against Civix. On August 14, 2012, the Company amended its complaint against Civix to assert an affirmative claim against Civix for breach of contract, alleging Civix violated its license agreement with, and covenant not to sue, one of the Company's technology licensors. On August 30, 2012, the Eastern District of Virginia transferred Civix’s case against LoopNet to the Northern District of Illinois, where both cases are now pending. On October 29, 2012, Civix filed a separate action against LoopNet in the Northern District of Illinois alleging infringement of U.S. Patent No. 8,296,335. That case was later consolidated with Civix’s original lawsuit against LoopNet. Civix amended its complaint against the Company on November 8, 2012 to add claims under Patent No. 8,296,335 as well. On November 15, 2012, LoopNet filed an amended answer and counterclaim against Civix, asserting an affirmative claim against Civix for breach of contract, alleging Civix violated its license agreement with, and covenant not to sue, one of LoopNet's technology licensors. The U.S. District Court for the Northern District of Illinois construed the language of the patent on September 23, 2013, but no trial date has been set. On November 25, 2013, Civix submitted its expert’s report of damages, which estimated the payment it deemed appropriate in the event that the Company is found liable for infringement. The Company believes that Civix’s calculation of damages is based on improper assumptions and miscalculations, and is otherwise unsupported. The Company submitted its own expert’s report of damages, which concluded that the appropriate payment to be made in the event that the Company is found liable for infringement is significantly less than Civix’s estimate of appropriate damages. Moreover, the Company’s expert’s report of damages concluded that while Civix’s calculation of damages was fundamentally flawed and should not be used to determine damages, simply applying certain necessary adjustments to Civix’s calculation as outlined in the Company’s report resulted in a significant reduction in Civix’s calculation of damages to approximately $3.7 million. On October 6, 2014 the Company offered to settle all outstanding litigation with Civix for $1.5 million. The Court subsequently granted a motion submitted by the parties requesting a settlement conference, which is scheduled to take place on November 20, 2014. At this time the Company cannot predict the outcome of its litigation with Civix, but the Company intends to vigorously defend itself against Civix’s claims.  While the Company believes it has meritorious defenses against Civix’s claims, the Company estimates that, based on the Company’s adjusted calculation of Civix’s alleged damages, the matter could result in a loss of up to $2.2 million in excess of the amount accrued.
	Currently, and from time to time, the Company is involved in litigation incidental to the conduct of its business. In accordance with GAAP, the Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. At the present time, while it is reasonably possible that an unfavorable outcome may occur as a result of one or more of the Company’s current litigation matters, management has concluded that it is not probable that a loss has been incurred in connection with the Company’s current litigation other than as described above. In addition, other than as described above, the Company is unable to estimate the possible loss or range of loss that could result from an unfavorable outcome in the Company’s current litigation and accordingly, the Company has not recognized any liability in the condensed consolidated financial statements for unfavorable results, if any, other than described above. Legal defense costs are expensed as incurred.

SEGMENT_REPORTING

SEGMENT REPORTING	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
SEGMENT REPORTING	'
	SEGMENT REPORTING
	The Company manages its business geographically in two operating segments, with the primary areas of measurement and decision-making being North America, which includes the U.S. and Canada, and International, which includes the U.K. and France. The Company’s subscription-based information services consist primarily of CoStar SuiteTM services. CoStar Suite is sold as a platform of service offerings consisting of CoStar Property Professional®, CoStar COMPS Professional® and CoStar Tenant® and through the Company's mobile application, CoStarGo®. CoStar Suite is the Company's primary service offering in the North America and International operating segments. Prior to the third quarter of 2014, FOCUSTM was the Company's primary service offering in the International operating segment. The Company introduced CoStar Suite in the U.K. in the fourth quarter of 2012 and no longer offered FOCUS to new clients beginning in 2013. CoStar's and its subsidiaries' subscription-based services consist primarily of similar services offered over the Internet to commercial real estate industry and related professionals. Management relies on an internal management reporting process that provides revenue and operating segment EBITDA, which is the Company's net income before interest, income taxes, depreciation and amortization. Management believes that operating segment EBITDA is an appropriate measure for evaluating the operational performance of the Company's operating segments. EBITDA is used by management to internally measure operating and management performance and to evaluate the performance of the business. However, this measure should be considered in addition to, not as a substitute for or superior to, income from operations or other measures of financial performance prepared in accordance with GAAP.
	Summarized information by operating segment consists of the following (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Revenues
	North America	$	146,899		$	107,230		$	402,074		$	310,762
	International
	External customers	6,157			5,071			17,766			14,571
	Intersegment revenue	5			131			41			277
	Total International revenue	6,162			5,202			17,807			14,848
	Intersegment eliminations	(5		)	(131		)	(41		)	(277		)
	Total revenues	$	153,056		$	112,301		$	419,840		$	325,333
	EBITDA
	North America	$	42,929		$	30,855		$	106,387		$	66,609
	International	763			(1,063		)	1,876			(3,917		)
	Total EBITDA	$	43,692		$	29,792		$	108,263		$	62,692
	The reconciliation of EBITDA to net income consists of the following (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	EBITDA	$	43,692		$	29,792		$	108,263		$	62,692
	Purchase amortization in cost of revenues	(7,790		)	(2,954		)	(18,547		)	(9,007		)
	Purchase amortization in operating expenses	(8,361		)	(3,680		)	(20,696		)	(11,699		)
	Depreciation and other amortization	(4,061		)	(3,388		)	(11,490		)	(9,531		)
	Interest income	46			52			245			239
	Interest expense	(2,698		)	(1,736		)	(8,066		)	(5,249		)
	Income tax expense, net	(7,871		)	(7,034		)	(18,763		)	(10,510		)
	Net income	$	12,957		$	11,052		$	30,946		$	16,935
	11	SEGMENT REPORTING — (CONTINUED)
	Intersegment revenue recorded during 2014 was attributable to services performed for the Company’s wholly owned subsidiary, CoStar Portfolio Strategy by Grecam S.A.S. (“Grecam”), a wholly owned subsidiary of CoStar Limited, the Company's wholly owned U.K. holding company. Intersegment revenue recorded during 2013 was attributable to services performed for CoStar Portfolio Strategy by Property and Portfolio Research Ltd., a wholly owned subsidiary of CoStar Portfolio Strategy. Intersegment revenue is recorded at an amount the Company believes approximates fair value. North America EBITDA includes a corresponding cost for the services performed by Grecam and Property and Portfolio Research Ltd. for CoStar Portfolio Strategy.
	North America EBITDA includes an allocation of approximately $200,000 and $300,000 for the three months ended September 30, 2014 and 2013, respectively. North America EBITDA includes an allocation of approximately $900,000 and $600,000 for the nine months ended September 30, 2014 and 2013, respectively. This allocation represents costs incurred for International employees involved in development activities of the Company's North America operating segment.
	International EBITDA includes a corporate allocation of approximately $100,000 for each of the three months ended September 30, 2014 and 2013. International EBITDA includes a corporate allocation of approximately $200,000 and $300,000 for the nine months ended September 30, 2014 and 2013, respectively. This allocation represents costs incurred for North America employees involved in management and expansion activities of the Company's International operating segment.
	11	SEGMENT REPORTING — (CONTINUED)
	Summarized information by operating segment consists of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Property and equipment, net
	North America	$	67,712		$	53,733
	International	2,963			3,986
	Total property and equipment, net	$	70,675		$	57,719
	Goodwill
	North America	$	1,114,363		$	692,639
	International	25,554			25,948
	Total goodwill	$	1,139,917		$	718,587
	Assets
	North America	$	2,118,504		$	1,311,292
	International	42,969			43,464
	Total operating segment assets	$	2,161,473		$	1,354,756
	Reconciliation of operating segment assets to total assets
	Total operating segment assets	$	2,161,473		$	1,354,756
	Investment in subsidiaries	(18,344		)	(18,344		)
	Intersegment receivables	(78,788		)	(79,430		)
	Total assets	$	2,064,341		$	1,256,982
	Liabilities
	North America	$	566,996		$	324,626
	International	78,145			79,266
	Total operating segment liabilities	$	645,141		$	403,892
	Reconciliation of operating segment liabilities to total liabilities
	Total operating segment liabilities	$	645,141		$	403,892
	Intersegment payables	(73,173		)	(74,772		)
	Total liabilities	$	571,968		$	329,120

EQUITY_OFFERING

EQUITY OFFERING	9 Months Ended
	Sep. 30, 2014
Proceeds from (Repurchase of) Equity [Abstract]	'
EQUITY OFFERING	'
	EQUITY OFFERING
	During June 2014, the Company completed a public equity offering of 3,450,000 shares of common stock for $160.00 per share. Net proceeds from the public equity offering were approximately $529.4 million, after deducting approximately $22.1 million of underwriting discounts and commissions and offering expenses of approximately $500,000. The Company intends to use the net proceeds from the sale of the securities to fund all or a portion of the costs of any strategic acquisitions it determines to pursue in the future, to finance the growth of its business and for working capital and other general corporate purposes. General corporate purposes may include additions to working capital, capital expenditures, repayment of debt, investments in the Company’s subsidiaries, possible acquisitions and the repurchase, redemption or retirement of securities, including the Company’s common stock.

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Accounting policies are consistent for each operating segment.
Use of Estimates	'
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Foreign Currency Translation	'
	Foreign Currency Translation
	The Company’s functional currency in its foreign locations is the local currency. Assets and liabilities are translated into U.S. dollars as of the balance sheet dates. Revenues, expenses, gains and losses are translated at the average exchange rates in effect during each period. Gains and losses resulting from translation are included in accumulated other comprehensive income (loss). Net gains or losses resulting from foreign currency exchange transactions are included in the condensed consolidated statements of operations. There were no material gains or losses from foreign currency exchange transactions for the three and nine months ended September 30, 2014 and 2013.
Accumulated Other Comprehensive Loss	'
	Accumulated Other Comprehensive Loss
	The components of accumulated other comprehensive loss were as follows (in thousands):
		September 30,			December 31,
		2014			2013
	Foreign currency translation adjustment	$	(4,455	)	$	(4,003	)
	Accumulated net unrealized loss on investments, net of tax	(1,286		)	(1,527		)
	Total accumulated other comprehensive loss	$	(5,741	)	$	(5,530	)
	There were no amounts reclassified out of accumulated other comprehensive loss to the condensed consolidated statements of operations for the three and nine months ended September 30, 2014 and 2013.
Net Income Per Share	'
	Net Income Per Share
	Net income per share is computed by dividing net income by the weighted average number of common shares outstanding during the period on a basic and diluted basis. The Company’s potentially dilutive securities include stock options and restricted stock. Diluted net income per share considers the impact of potentially dilutive securities except in periods in which there is a net loss, as the inclusion of the potentially dilutive common shares would have an anti-dilutive effect.
Stock-Based Compensation	'
	Stock-Based Compensation
	Equity instruments issued in exchange for employee services are accounted for using a fair-value based method and the fair value of such equity instruments is recognized as expense in the condensed consolidated statements of operations.
	Stock-based compensation expense is measured at the grant date of the stock-based awards that vest over set time periods based on their fair values, and is recognized on a straight line basis as expense over the vesting periods of the awards, net of an estimated forfeiture rate. For equity instruments that vest based on performance, the Company assesses the probability of the achievement of the performance conditions at the end of each reporting period, or more frequently based upon the occurrence of events that may change the probability of whether the performance conditions would be met. If the Company's initial estimates of the achievement of the performance conditions change, the related stock-based compensation expense and timing of recognition may fluctuate from period to period based on those estimates. If the performance conditions are not met, no stock-based compensation expense will be recognized, and any previously recognized stock-based compensation expense will be reversed.
	In 2012, the Company granted performance-based restricted common stock awards that vest upon the Company's achievement of $90.0 million of cumulative net income before interest, income taxes, depreciation and amortization ("EBITDA") over a period of four consecutive calendar quarters if such performance is achieved by March 31, 2017, subject to certain approvals under the CoStar Group, Inc. 2007 Stock Incentive Plan. As of March 31, 2014, the Company had satisfied all performance and service conditions, and as a result, the restricted common stock granted under these awards vested. The Company recorded approximately $0 and $3.1 million of stock-based compensation expense related to the 2012 performance-based restricted common stock for the three months ended September 30, 2014 and 2013, respectively. The Company recorded approximately $2.2 million and $17.5 million of stock-based compensation expense related to the 2012 performance-based restricted common stock for the nine months ended September 30, 2014 and 2013, respectively.
	Cash flows resulting from excess tax benefits are classified as part of cash flows from operating and financing activities. Excess tax benefits represent tax benefits related to stock-based compensation in excess of the associated deferred tax asset for such equity compensation.
Capitalized Product Development Costs	'
	Capitalized Product Development Costs
	Product development costs are expensed as incurred until technological feasibility has been established, at which time such costs are capitalized. Costs are capitalized, to the extent that the capitalizable costs do not exceed the realizable value of such costs, until the product is available for general release to customers. The Company defines the establishment of technological feasibility as the completion of all planning, designing, coding and testing activities that are necessary to establish products that meet design specifications including functions, features and technical performance requirements. The Company's capitalized product development costs had a total net book value of approximately $0 and $111,000 as of September 30, 2014 and December 31, 2013, respectively. These capitalized product development costs are included in intangible and other assets in the Company’s condensed consolidated balance sheets. Amortization is computed using a straight-line method over the remaining estimated economic life of the product, typically three to five years after the software is ready for its intended use. The Company amortized capitalized product development costs of approximately $16,000 and $48,000 for the three months ended September 30, 2014 and 2013, respectively. The Company amortized capitalized product development costs of approximately $111,000 and $143,000 for the nine months ended September 30, 2014 and 2013, respectively.
Debt Issuance Costs	'
	Debt Issuance Costs
	Costs incurred in connection with the issuance of long-term debt are capitalized and amortized as interest expense over the term of the related debt using the effective interest method. Upon a refinancing, previously capitalized debt issuance costs are expensed and included in loss on extinguishment of debt if the Company determines that there has been a substantial modification of the related debt. If the Company determines that there has not been a substantial modification of the related debt, any previously capitalized debt issuance costs are amortized as interest expense over the term of the new debt instrument using the effective interest method. The Company had capitalized debt issuance costs of approximately $14.1 million and $6.5 million as of September 30, 2014 and December 31, 2013, respectively. The debt issuance costs are associated with the financing commitment received from JPMorgan Chase Bank, N.A. (“J.P. Morgan Bank”) on April 27, 2011, the subsequent term loan facility and revolving credit facility established under a credit agreement dated February 16, 2012 (the “2012 Credit Agreement”), the financing commitment received from J.P. Morgan Bank, Bank of America, N.A., SunTrust Bank and Wells Fargo Bank, National Association on February 28, 2014, and the subsequent term loan facility and revolving credit facility established under a credit agreement dated April 1, 2014 (the “2014 Credit Agreement”). See Note 8 for additional information regarding the term loan facility and revolving credit facility. The Company amortized debt issuance costs of approximately $904,000 and $760,000 for the three months ended September 30, 2014 and 2013, respectively. The Company amortized debt issuance costs of approximately $2.5 million and $2.3 million for the nine months ended September 30, 2014 and 2013, respectively.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	There have been no developments to the Recent Accounting Pronouncements discussion included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013, including the expected dates of adoption and estimated effects on the Company’s condensed consolidated financial statements, except for the following:
	In May 2014, the Financial Accounting Standards Board (“FASB”) and International Accounting Standards Board (“IASB”) jointly issued a new revenue recognition standard that will improve financial reporting by creating common recognition guidance for U.S. GAAP and International Financial Reporting Standards (“IFRS”). This guidance removes inconsistencies and weaknesses in revenue requirements, provides a more robust framework for addressing revenue issues, improves the comparability of revenue recognition practices across industries, provides more useful information to users of financial statements through improved disclosure requirements and simplifies the presentation of financial statements. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This guidance is effective on a retrospective basis for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. Early application is not permitted. The Company is evaluating the impact this guidance will have on its financial statements.

SUMMARY_OF_SIGNIFICANT_ACCOUNT2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Schedule of accumulated other comprehensive loss	'
	The components of accumulated other comprehensive loss were as follows (in thousands):
		September 30,				December 31,
		2014				2013
	Foreign currency translation adjustment	$	(4,455	)		$	(4,003	)
	Accumulated net unrealized loss on investments, net of tax	(1,286		)		(1,527		)
	Total accumulated other comprehensive loss	$	(5,741	)		$	(5,530	)
Calculation of basic and diluted net income per share	'
	The following table sets forth the calculation of basic and diluted net income per share (in thousands, except per share data):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014		2013
	Numerator:
	Net income	$	12,957			$	11,052		$	30,946	$	16,935
	Denominator:
	Denominator for basic net income per share — weighted-average outstanding shares	31,742				27,758			29,692		27,607
	Effect of dilutive securities:
	Stock options and restricted stock	333				591			442		530
	Denominator for diluted net income per share — weighted-average outstanding shares	32,075				28,349			30,134		28,137
	Net income per share — basic	$	0.41			$	0.4		$	1.04	$	0.61
	Net income per share — diluted	$	0.4			$	0.39		$	1.03	$	0.6
Schedule of anti-dilutive securities excluded from computation of earnings per share [Table Text Block]	'
	The following table summarizes the potential common shares excluded from the diluted calculation (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014		2013
	Employee stock options	80			—			80		—
Stock-based compensation expense for stock options and restricted stock	'
	Stock-based compensation expense for stock options and restricted stock issued under equity incentive plans and stock purchases under the ESPP included in the Company’s results of operations were as follows (in thousands):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014		2013
	Cost of revenues	$	1,067			$	1,061		$	3,331	$	3,353
	Selling and marketing	954				944			2,729		3,763
	Software development	1,179				1,608			3,867		5,439
	General and administrative	3,447				4,175			10,979		19,715
	Total stock-based compensation	$	6,647			$	7,788		$	20,906	$	32,270

ACQUISITION_Tables

ACQUISITION (Tables)	9 Months Ended
	Sep. 30, 2014
Business Acquisition [Line Items]	'
Schedule of assets acquired and liabilities assumed	'
	The following table summarizes the amounts for acquired assets and liabilities recorded at their fair values as of the acquisition date (in thousands):
	Accounts receivable	$	11,402
	Goodwill	421,724
	Acquired trade names and other	71,779
	Acquired customer base	69,684
	Acquired database technology	11,489
	Acquired building photography	1,006
	Other assets and liabilities	(2,866		)
	Fair value of identifiable net assets acquired	$	584,218
Schedule of pro forma information	'
	The following unaudited pro forma amounts present consolidated information as if the acquisition had been completed as of January 1, 2013 (in thousands except per share data):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2014			2013		2014		2013
	Revenue	$	153,056		$	134,328	$	442,244	$	389,059
	Net income	$	16,044		$	7,439	$	34,694	$	5,381
	Net income per share — basic	$	0.51		$	0.27	$	1.17	$	0.19
	Net income per share — diluted	$	0.5		$	0.26	$	1.15	$	0.19

INVESTMENTS_Tables

INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
Scheduled maturities of investments classified as available-for-sale	'
	Scheduled maturities of investments classified as available-for-sale as of September 30, 2014 are as follows (in thousands):
	Maturity		Fair Value
	Due:
	October 1, 2014 — September 30, 2015		$	—
	October 1, 2015 — September 30, 2019		816
	October 1, 2019 — September 30, 2024		—
	After September 30, 2024		20,265
	Available-for-sale investments		$	21,081
Schedule of available for sale securities reconciliation	'
	As of September 30, 2014, the amortized cost basis and fair value of investments classified as available-for-sale were as follows (in thousands):
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Gains			Losses
	Auction rate securities	$	22,367		$	374		$	(1,660	)	$	21,081
	Available-for-sale investments	$	22,367		$	374		$	(1,660	)	$	21,081
	As of December 31, 2013, the amortized cost basis and fair value of investments classified as available-for-sale were as follows (in thousands):
		Amortized			Gross			Gross			Fair
		Cost			Unrealized			Unrealized			Value
					Gains			Losses
	Auction rate securities	$	23,517		$	411		$	(1,938	)	$	21,990
	Available-for-sale investments	$	23,517		$	411		$	(1,938	)	$	21,990
Schedule of unrealized loss on investments for twelve months or longer	'
	The components of the Company’s investments in an unrealized loss position for twelve months or longer were as follows (in thousands):
		September 30,						December 31,
		2014						2013
		Aggregate			Gross			Aggregate			Gross
		Fair			Unrealized			Fair			Unrealized
		Value			Losses			Value			Losses
	Auction rate securities	$	20,265		$	(1,660	)	$	21,137		$	(1,938	)
	Investments in an unrealized loss position	$	20,265		$	(1,660	)	$	21,137		$	(1,938	)

FAIR_VALUE_Tables

FAIR VALUE (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Summary of fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis	'
	The following table represents the Company's fair value hierarchy for its financial assets (cash, cash equivalents and investments) measured at fair value on a recurring basis as of September 30, 2014 (in thousands):
		Level 1			Level 2		Level 3			Total
	Assets:
	Cash	$	482,728		$	—	$	—		$	482,728
	Money market funds	655			—		—			655
	Commercial paper	2,812			—		—			2,812
	Auction rate securities	—			—		21,081			21,081
	Total assets measured at fair value	$	486,195		$	—	$	21,081		$	507,276
	The following table represents the Company's fair value hierarchy for its financial assets (cash, cash equivalents and investments) and liabilities measured at fair value on a recurring basis as of December 31, 2013 (in thousands):
		Level 1			Level 2		Level 3			Total
	Assets:
	Cash	$	134,989		$	—	$	—		$	134,989
	Money market funds	50,593			—		—			50,593
	Commercial paper	70,371			—		—			70,371
	Auction rate securities	—			—		21,990			21,990
	Total assets measured at fair value	$	255,953		$	—	$	21,990		$	277,943
	Liabilities:
	Deferred consideration	$	—		$	—	$	1,344		$	1,344
	Total liabilities measured at fair value	$	—		$	—	$	1,344		$	1,344
Summary of changes in the fair value of the company's level 3 assets	'
	The following tables summarize changes in fair value of the Company’s Level 3 assets for the three and nine months ended September 30, 2014 and 2013 (in thousands):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2014			2013		2014			2013
	Balance at beginning of period	$	21,639		$	21,675	$	21,990		$	21,662
	Decrease in unrealized loss included in accumulated other comprehensive loss	42			—		241			63
	Settlements	(600		)	—		(1,150		)	(50		)
	Balance at end of period	$	21,081		$	21,675	$	21,081		$	21,675
	5	FAIR VALUE — (CONTINUED)
	The following table summarizes changes in fair value of the Company’s Level 3 assets from December 31, 2007 to September 30, 2014 (in thousands):
		Auction
		Rate
		Securities
	Balance at December 31, 2007	$	53,975
	Increase in unrealized loss included in accumulated other comprehensive loss	(3,710		)
	Settlements	(20,925		)
	Balance at December 31, 2008	29,340
	Decrease in unrealized loss included in accumulated other comprehensive loss	684
	Settlements	(300		)
	Balance at December 31, 2009	29,724
	Decrease in unrealized loss included in accumulated other comprehensive loss	40
	Settlements	(575		)
	Balance at December 31, 2010	29,189
	Decrease in unrealized loss included in accumulated other comprehensive loss	245
	Settlements	(4,850		)
	Balance at December 31, 2011	24,584
	Auction rate securities upon acquisition	442
	Decrease in unrealized loss included in accumulated other comprehensive loss	836
	Settlements	(4,200		)
	Balance at December 31, 2012	21,662
	Decrease in unrealized loss included in accumulated other comprehensive loss	378
	Settlements	(50		)
	Balance at December 31, 2013	21,990
	Decrease in unrealized loss included in accumulated other comprehensive loss	241
	Settlements	(1,150		)
	Balance at September 30, 2014	$	21,081
Summary of changes in the fair value of the company's level 3 liabilities	'
	The following tables summarize changes in fair value of the Company’s Level 3 liabilities for the three and nine months ended September 30, 2014 and 2013 (in thousands):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2014			2013		2014			2013
	Balance at beginning of period	$	—		$	1,146	$	1,344		$	2,304
	Accretion for period	—			62		—			248
	Payments made during period	—			—		(1,344		)	(1,344		)
	Balance at end of period	$	—		$	1,208	$	—		$	1,208
	The following table summarizes changes in fair value of the Company’s Level 3 liabilities from December 31, 2012 to September 30, 2014 (in thousands):
		Deferred
		Consideration
	Balance at December 31, 2012	$	2,304
	Accretion for 2013	384
	Payments made in 2013	(1,344		)
	Balance at December 31, 2013	1,344
	Payments made from January 1, 2014 – September 30, 2014	(1,344		)
	Balance at September 30, 2014	$	—

GOODWILL_Tables

GOODWILL (Tables)	9 Months Ended
	Sep. 30, 2014
Goodwill [Abstract]	'
Schedule of Goodwill	'
	The changes in the carrying amount of goodwill by operating segment consist of the following (in thousands):
		North America		International			Total
	Goodwill, December 31, 2012	$	692,639	$	25,439		$	718,078
	Effect of foreign currency translation	—		509			509
	Goodwill, December 31, 2013	692,639		25,948			718,587
	Acquisition	421,724		—			421,724
	Effect of foreign currency translation	—		(394		)	(394		)
	Goodwill, September 30, 2014	$	1,114,363	$	25,554		$	1,139,917

INTANGIBLES_AND_OTHER_ASSETS_T

INTANGIBLES AND OTHER ASSETS (Tables)	9 Months Ended
	Sep. 30, 2014
Intangibles and Other Assets [Abstract]	'
Schedule of acquired finite-lived intangible assets by major class	'
	Intangibles and other assets consist of the following (in thousands, except amortization period data):
		September 30,			December 31,			Weighted-
		2014			2013			Average
								Amortization
								Period (in years)
	Capitalized product development cost	$	2,140		$	2,140		4
	Accumulated amortization	(2,140		)	(2,029		)
	Capitalized product development cost, net	—			111
	Building photography	14,918			13,743			5
	Accumulated amortization	(12,533		)	(12,005		)
	Building photography, net	2,385			1,738
	Acquired database technology	88,826			77,368			4
	Accumulated amortization	(54,981		)	(41,073		)
	Acquired database technology, net	33,845			36,295
	Acquired customer base	200,430			130,960			10
	Accumulated amortization	(95,264		)	(74,734		)
	Acquired customer base, net	105,166			56,226
	Acquired trade names and other (1)	128,349			59,336			13
	Accumulated amortization	(12,568		)	(9,234		)
	Acquired trade names and other, net	115,781			50,102
	Intangibles and other assets, net	$	257,177		$	144,472
	(1) The weighted-average amortization period for acquired trade names excludes $48.7 million for acquired trade names recorded in connection with the LoopNet acquisition on April 30, 2012, which amount is not amortized, but is subject to annual impairment tests.

SEGMENT_REPORTING_Tables

SEGMENT REPORTING (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Summarized information by operating segment	'
	Summarized information by operating segment consists of the following (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Revenues
	North America	$	146,899		$	107,230		$	402,074		$	310,762
	International
	External customers	6,157			5,071			17,766			14,571
	Intersegment revenue	5			131			41			277
	Total International revenue	6,162			5,202			17,807			14,848
	Intersegment eliminations	(5		)	(131		)	(41		)	(277		)
	Total revenues	$	153,056		$	112,301		$	419,840		$	325,333
	EBITDA
	North America	$	42,929		$	30,855		$	106,387		$	66,609
	International	763			(1,063		)	1,876			(3,917		)
	Total EBITDA	$	43,692		$	29,792		$	108,263		$	62,692
Reconciliation of EBITDA to net income	'
	The reconciliation of EBITDA to net income consists of the following (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	EBITDA	$	43,692		$	29,792		$	108,263		$	62,692
	Purchase amortization in cost of revenues	(7,790		)	(2,954		)	(18,547		)	(9,007		)
	Purchase amortization in operating expenses	(8,361		)	(3,680		)	(20,696		)	(11,699		)
	Depreciation and other amortization	(4,061		)	(3,388		)	(11,490		)	(9,531		)
	Interest income	46			52			245			239
	Interest expense	(2,698		)	(1,736		)	(8,066		)	(5,249		)
	Income tax expense, net	(7,871		)	(7,034		)	(18,763		)	(10,510		)
	Net income	$	12,957		$	11,052		$	30,946		$	16,935
Summarized information by operating segment, assets and liabilities	'
	Summarized information by operating segment consists of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Property and equipment, net
	North America	$	67,712		$	53,733
	International	2,963			3,986
	Total property and equipment, net	$	70,675		$	57,719
	Goodwill
	North America	$	1,114,363		$	692,639
	International	25,554			25,948
	Total goodwill	$	1,139,917		$	718,587
	Assets
	North America	$	2,118,504		$	1,311,292
	International	42,969			43,464
	Total operating segment assets	$	2,161,473		$	1,354,756
	Reconciliation of operating segment assets to total assets
	Total operating segment assets	$	2,161,473		$	1,354,756
	Investment in subsidiaries	(18,344		)	(18,344		)
	Intersegment receivables	(78,788		)	(79,430		)
	Total assets	$	2,064,341		$	1,256,982
	Liabilities
	North America	$	566,996		$	324,626
	International	78,145			79,266
	Total operating segment liabilities	$	645,141		$	403,892
	Reconciliation of operating segment liabilities to total liabilities
	Total operating segment liabilities	$	645,141		$	403,892
	Intersegment payables	(73,173		)	(74,772		)
	Total liabilities	$	571,968		$	329,120

ORGANIZATION_Details

ORGANIZATION (Details)	9 Months Ended
	Sep. 30, 2014
	operating_segments
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Number of business segments (in segments)	2
Term of subscription-based license agreements (in years)	'1 year

SUMMARY_OF_SIGNIFICANT_ACCOUNT3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, NET INCOME PER SHARE (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator: [Abstract]	'	'	'	'
Net income	$12,957	$11,052	$30,946	$16,935
Denominator: [Abstract]	'	'	'	'
Denominator for basic net income per share - weighted-average outstanding shares (in shares)	31,742	27,758	29,692	27,607
Effect of dilutive securities: [Abstract]	'	'	'	'
Stock options and restricted stock	333	591	442	530
Denominator for diluted net income per share - weighted-average outstanding shares (in shares)	32,075	28,349	30,134	28,137
Net income per share - basic (in dollars per share)	$0.41	$0.40	$1.04	$0.61
Net income per share - diluted (in dollars per share)	$0.40	$0.39	$1.03	$0.60
Antidilutive securities excluded from computation of earnings per share	80	0	80	0

SUMMARY_OF_SIGNIFICANT_ACCOUNT4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, ACCUMULATED OTHER COMPREHENSIVE LOSS, NET OF TAX (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Accounting Policies [Abstract]	'	'	'	'	'
Material gains or losses from foreign currency transactions	$0	$0	$0	$0	'
Accumulated Other Comprehensive Loss Net of Tax [Abstract]	'	'	'	'	'
Foreign currency translation adjustment	-4,455	'	-4,455	'	-4,003
Accumulated net unrealzied loss on investments, net of tax	-1,286	'	-1,286	'	-1,527
Total accumulated other comprehensive loss	-5,741	'	-5,741	'	-5,530
Reclassification out of accumulated other comprehensive loss	$0	$0	$0	$0	'

SUMMARY_OF_SIGNIFICANT_ACCOUNT5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, STOCK BASED COMPENSATION EXPENSE (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock-Based Compensation Expense [Abstract]	'	'	'	'
Compensation expense	$6,647,000	$7,788,000	$20,906,000	$32,270,000
Net cash proceeds from the exercise of stock options and ESPP	1,610,000	6,935,000	5,157,000	15,846,000
Excess tax benefits realized from stock option exercised and restricted stock awards vested	1,348,000	5,655,000	28,167,000	15,405,000
Exercise of stock options (in shares)	20,366	150,560	66,201	340,599
Cost of Revenues [Member]	'	'	'	'
Stock-Based Compensation Expense [Abstract]	'	'	'	'
Compensation expense	1,067,000	1,061,000	3,331,000	3,353,000
Selling and Marketing [Member]	'	'	'	'
Stock-Based Compensation Expense [Abstract]	'	'	'	'
Compensation expense	954,000	944,000	2,729,000	3,763,000
Software Development [Member]	'	'	'	'
Stock-Based Compensation Expense [Abstract]	'	'	'	'
Compensation expense	1,179,000	1,608,000	3,867,000	5,439,000
General and Administrative [Member]	'	'	'	'
Stock-Based Compensation Expense [Abstract]	'	'	'	'
Compensation expense	3,447,000	4,175,000	10,979,000	19,715,000
Performance-Based Restricted Common Stock [Member]	'	'	'	'
Stock-Based Compensation Expense [Abstract]	'	'	'	'
Cumulative EBITDA required for award shares to vest	90,000,000	'	90,000,000	'
Number of consecutive quarters to mantain cumulative EBITDA required for award shares to vest	4	'	4	'
Compensation expense	$0	$3,100,000	$2,200,000	$17,500,000

SUMMARY_OF_SIGNIFICANT_ACCOUNT6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, CAPITALIZED PRODUCT DEVELOPMENT AND DEBT ISSUANCE COSTS (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Apr. 01, 2014	Dec. 31, 2013
Capitalized Product Development Costs [Abstract]	'	'	'	'	'	'
Finite-lived intangible assets, net	$257,177,000	'	$257,177,000	'	'	$144,472,000
Amortization expense of capitalized product development costs	8,361,000	3,680,000	20,696,000	11,699,000	'	'
Debt Issuance Cost [Abstract]	'	'	'	'	'	'
Capitalized debt issuance costs	14,052,000	'	14,052,000	'	10,000,000	6,542,000
Amortization of debt issuance costs	904,000	760,000	2,459,000	2,273,000	'	'
Minimum [Member]	'	'	'	'	'	'
Capitalized Product Development Costs [Abstract]	'	'	'	'	'	'
Finite-lived intangible asset, useful life (in years)	'	'	'3 years	'	'	'
Maximum [Member]	'	'	'	'	'	'
Capitalized Product Development Costs [Abstract]	'	'	'	'	'	'
Finite-lived intangible asset, useful life (in years)	'	'	'5 years	'	'	'
Capitalized Product Development Costs [Member]	'	'	'	'	'	'
Capitalized Product Development Costs [Abstract]	'	'	'	'	'	'
Finite-lived intangible assets, net	0	'	0	'	'	111,000
Amortization expense of capitalized product development costs	$16,000	$48,000	$111,000	$143,000	'	'

ACQUISITION_Details

ACQUISITION (Details) (USD $)

0 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

Apr. 03, 2014

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Dec. 31, 2012

Apr. 03, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Apr. 01, 2014

Sep. 30, 2014

Apr. 03, 2014

Apr. 01, 2014

Sep. 30, 2014

Apr. 03, 2014

Sep. 30, 2014

Apr. 03, 2014

Sep. 30, 2014

Apr. 03, 2014

Apartments.com [Member]

Apartments.com [Member]

Apartments.com [Member]

Apartments.com [Member]

Apartments.com [Member]

Apartments.com [Member]

Customer Contracts [Member]

Customer Contracts [Member]

Customer Contracts [Member]

Developed Technology Rights [Member]

Developed Technology Rights [Member]

Trade Names and Other [Member]

Trade Names and Other [Member]

Building Photography [Member]

Building Photography [Member]

Apartments.com [Member]

Apartments.com [Member]

Apartments.com [Member]

Apartments.com [Member]

Apartments.com [Member]

distinct_intangible_asset

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments to acquire businesses

$587,104,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Closing purchase price adjustments

2,104,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Post closing purchase price adjustments

2,886,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of distinct intangible assets

'

'

'

'

'

'

'

'

'

'

'

'

'

1

'

'

'

'

'

'

Estimated useful life of acquired assets

'

'

'

'

'

'

'

'

'

'

'

'10 years

'10 years

'

'4 years

'1 year

'13 years

'13 years

'5 years

'3 years

Goodwill

'

1,139,917,000

'

718,587,000

718,078,000

'

'

'

'

'

421,724,000

'

'

'

'

'

'

'

'

'

Goodwill tax deductible amount

'

'

'

'

'

'

'

'

'

'

421,724,000

'

'

'

'

'

'

'

'

'

Consolidated revenue from acquisition

'

'

'

'

'

'

26,000,000

0

51,100,000

0

'

'

'

'

'

'

'

'

'

'

Consolidated loss before income taxes from acquisition

'

'

'

'

'

'

-7,500,000

0

-15,700,000

0

'

'

'

'

'

'

'

'

'

'

Effective income tax rate (in percent)

'

38.00%

38.00%

'

'

38.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business combination, acquisition related costs

'

'

'

'

'

'

$0

$0

$1,400,000

$0

'

'

'

'

'

'

'

'

'

'

ACQUSITION_ACQUISITION_Details

ACQUSITION ACQUISITION (Details - Schedule of Assets Acquired and Liabilities Assumed) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 01, 2014	Apr. 01, 2014	Apr. 01, 2014	Apr. 01, 2014	Apr. 01, 2014
In Thousands, unless otherwise specified				Apartments.com [Member]	Apartments.com [Member]	Apartments.com [Member]	Apartments.com [Member]	Apartments.com [Member]
					Trade Names and Other [Member]	Customer Contracts [Member]	Developed Technology Rights [Member]	Building Photography [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'
Accounts receivable	'	'	'	$11,402	'	'	'	'
Goodwill	1,139,917	718,587	718,078	421,724	'	'	'	'
Intangible assets, other than goodwill	'	'	'	'	71,779	69,684	11,489	1,006
Other assets and liabilities	'	'	'	-2,866	'	'	'	'
Fair value of identifiable net assets acquired	'	'	'	$584,218	'	'	'	'

ACQUSITION_ACQUISITION_Details1

ACQUSITION ACQUISITION (Details - Schedule of Supplemental Pro Forma Information) (Apartments.com [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Apartments.com [Member]	'	'	'	'
Business Acquisition [Line Items]	'	'	'	'
Revenue	$153,056	$134,328	$442,244	$389,059
Net income	$16,044	$7,439	$34,694	$5,381
Net income per share - basic (in dollars per share)	$0.51	$0.27	$1.17	$0.19
Net income per share - diluted (in dollars per share)	$0.50	$0.26	$1.15	$0.19

INVESTMENTS_Details

INVESTMENTS (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'	'
Available-for-sale securities, gross realized gains	$0	$0	$0	$0	'
Available-for-sale securities, gross realized losses	0	0	0	0	'
Debt Maturities Fair Value [Abstract]	'	'	'	'	'
October 1, 2014 — September 30, 2015	0	'	0	'	'
October 1, 2015 — September 30, 2019	816,000	'	816,000	'	'
October 1, 2019 — September 30, 2024	0	'	0	'	'
After September 30, 2024	20,265,000	'	20,265,000	'	'
Fair Value	$21,081,000	'	$21,081,000	'	$21,990,000

INVESTMENTS_AVAILABLEFORSALE_S

INVESTMENTS, AVAILABLE-FOR-SALE SECURITIES (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	$0	$0
Available-for-sale Securities Reconciliation [Abstract]	'	'
Amortized Cost	22,367	23,517
Gross Unrealized Gains	374	411
Gross Unrealized Losses	-1,660	-1,938
Fair Value	21,081	21,990
Available-for-sale securities, unrealized loss positions	'	'
Aggregate Fair Value	20,265	21,137
Auction Rate Securities [Member]	'	'
Available-for-sale Securities Reconciliation [Abstract]	'	'
Amortized Cost	22,367	23,517
Gross Unrealized Gains	374	411
Gross Unrealized Losses	-1,660	-1,938
Fair Value	21,081	21,990
Available-for-sale securities, unrealized loss positions	'	'
Aggregate Fair Value	$20,265	$21,137

FAIR_VALUE_Details

FAIR VALUE (Details) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2009

Dec. 31, 2008

Mar. 31, 2014

Dec. 31, 2013

Mar. 28, 2013

Mar. 31, 2014

Dec. 31, 2013

Mar. 28, 2013

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Fair Value, Measurements, Recurring [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

LandsofAmerica [Member]

LandsofAmerica [Member]

LandsofAmerica [Member]

Reaction Web [Member]

Reaction Web [Member]

Reaction Web [Member]

Cash [Member]

Cash [Member]

Money Market Funds [Member]

Money Market Funds [Member]

Commercial Paper [Member]

Commercial Paper [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 1 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 2 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Fair Value, Inputs, Level 3 [Member]

Cash [Member]

Cash [Member]

Money Market Funds [Member]

Money Market Funds [Member]

Commercial Paper [Member]

Commercial Paper [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Cash [Member]

Cash [Member]

Money Market Funds [Member]

Money Market Funds [Member]

Commercial Paper [Member]

Commercial Paper [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Cash [Member]

Cash [Member]

Money Market Funds [Member]

Money Market Funds [Member]

Commercial Paper [Member]

Commercial Paper [Member]

Auction Rate Securities [Member]

Auction Rate Securities [Member]

Assets:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total assets measured at fair value

'

'

'

'

'

$507,276,000

$277,943,000

$482,728,000

$134,989,000

$655,000

$50,593,000

$2,812,000

$70,371,000

$21,081,000

$21,990,000

$486,195,000

$255,953,000

$482,728,000

$134,989,000

$655,000

$50,593,000

$2,812,000

$70,371,000

$0

$0

$0

$0

$0

$0

$0

$0

$0

$0

$0

$0

$21,081,000

$21,990,000

$0

$0

$0

$0

$0

$0

$21,081,000

$21,990,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Unobservable inputs assets (level 3) [Roll forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Beginning balance

21,639,000

21,675,000

21,990,000

21,662,000

21,662,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

21,990,000

21,662,000

24,584,000

29,189,000

29,724,000

29,340,000

53,975,000

'

'

'

'

'

'

Change in unrealized gain (loss) included in accumulated other comprehensive loss

42,000

0

241,000

63,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

241,000

378,000

836,000

245,000

40,000

684,000

-3,710,000

'

'

'

'

'

'

Settlements

-600,000

0

-1,150,000

-50,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,150,000

-50,000

-4,200,000

-4,850,000

-575,000

-300,000

-20,925,000

'

'

'

'

'

'

Auction rate securities upon acquisition

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

442,000

'

'

'

'

'

'

'

'

'

'

Ending balance

21,081,000

21,675,000

21,081,000

21,675,000

21,990,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

21,081,000

21,990,000

21,662,000

24,584,000

29,189,000

29,724,000

29,340,000

'

'

'

'

'

'

Auction rate securities variable rate debt instruments interest rate reset period

'

'

'28 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

The minimum contractual maturities on underlying securities involved in auction rate securities

'

'

'20 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Par value of company held auction rate securities

23,200,000

'

23,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Discount rate (in percent)

'

'

5.10%

'

4.90%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Temporary impairment of the auction rates security investments

-1,286,000

'

-1,286,000

'

-1,527,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Liabilities:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred consideration

'

'

'

'

'

'

1,344,000

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

0

1,344,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unobservable inputs liabilities (level 3) [Roll forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Beginning balance

0

1,146,000

1,344,000

2,304,000

2,304,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accretion

0

62,000

0

248,000

384,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments

0

0

-1,344,000

-1,344,000

-1,344,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ending balance

0

1,208,000

0

1,208,000

1,344,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business acquisition deferred consideration potential cash payment (undiscounted)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,000,000

'

'

344,000

'

Business acquisition deferred consideration cash payment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,000,000

'

$1,000,000

$344,000

'

$344,000

GOODWILL_Details

GOODWILL (Details) (USD $)	9 Months Ended	12 Months Ended	9 Months Ended		9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Apr. 01, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Dec. 31, 2013
			Apartments.com [Member]	Apartments.com [Member]	North America [Member]	North America [Member]	International [Member]	International [Member]
Goodwill [Line Items]	'	'	'	'	'	'	'	'
Goodwill, period increase	'	'	$421,724	'	'	'	'	'
Goodwill [Roll Forward]	'	'	'	'	'	'	'	'
Goodwill, beginning balance	718,587	718,078	'	421,724	692,639	692,639	25,948	25,439
Effect of foreign currency translation	-394	509	'	'	0	0	-394	509
Acquisition	421,724	'	'	'	421,724	'	0	'
Goodwill, ending balance	$1,139,917	$718,587	'	$421,724	$1,114,363	$692,639	$25,554	$25,948

INTANGIBLES_AND_OTHER_ASSETS_D

INTANGIBLES AND OTHER ASSETS (Details) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Apr. 30, 2012

Capitalized Product Development Costs [Member]

Capitalized Product Development Costs [Member]

Building Photography [Member]

Building Photography [Member]

Developed Technology Rights [Member]

Developed Technology Rights [Member]

Acquired Customer Base [Member]

Acquired Customer Base [Member]

Trade Names and Other [Member]

Trade Names and Other [Member]

LoopNet [Member]

Acquired Finite-Lived Intangible Assets [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business acquisition, purchase price allocation, intangible assets not amortizable

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$48,700,000

Finite-lived intangible assets, gross

'

'

'

'

'

2,140,000

2,140,000

14,918,000

13,743,000

88,826,000

77,368,000

200,430,000

130,960,000

128,349,000

59,336,000

'

Finite-lived intangible assets, accumulated amortization

'

'

'

'

'

-2,140,000

-2,029,000

-12,533,000

-12,005,000

-54,981,000

-41,073,000

-95,264,000

-74,734,000

-12,568,000

-9,234,000

'

Finite-lived intangible assets, net

257,177,000

'

257,177,000

'

144,472,000

0

111,000

2,385,000

1,738,000

33,845,000

36,295,000

105,166,000

56,226,000

115,781,000

50,102,000

'

Weighted-average amortization period (in years}

'

'

'

'

'

'4 years

'

'5 years

'

'4 years

'

'10 years

'

'13 years

'

'

Impairment of intangible assets, finite-lived

$746,000

$1,053,000

$1,799,000

$0

'

'

'

'

'

'

'

'

'

'

'

'

LONGTERM_DEBT_Details

LONG-TERM DEBT (Details) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended
	Apr. 03, 2014	Jun. 30, 2014	Apr. 04, 2014	Sep. 30, 2014	Apr. 01, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'	'	'	'	'
Line of credit facility, amount outstanding	'	'	'	'	$150,000,000	'
Repayments of revolving credit facility	'	150,000,000	'	'	'	'
Repayments of term loan	148,800,000	'	'	'	'	'
LIBOR maturity period (in months)	'1 month	'	'	'	'	'
Default interest rate per annum on overdue amounts (in percent)	'	'	'	'	2.00%	'
Credit facility, collateral	'The obligations under the 2014 Credit Agreement are guaranteed by all material subsidiaries of the Company and are secured by a lien on substantially all of the assets of the Company and those of its material subsidiaries, in each case subject to certain exceptions, pursuant to security and guarantee documents entered into on the Closing Date.	'	'	'	'	'
Debt issuance costs	'	'	10,100,000	'	'	'
Debt issuance underwriting fees	'	'	9,700,000	'	'	'
Debt Issuance Legal Fees	'	'	400,000	'	'	'
Capitalized debt issuance costs	'	'	'	14,052,000	10,000,000	6,542,000
Term Loan [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Debt instrument borrowing capacity	'	'	'	'	400,000,000	'
Term of loan (in years)	'5 years	'	'	'	'	'
Revolving Credit Facility [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Debt instrument borrowing capacity	'	'	'	'	225,000,000	'
Term of loan (in years)	'5 years	'	'	'	'	'
Line of credit facility, amount outstanding	'	'	'	0	'	0
CoStar Group [Member] | Term Loan [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Debt instrument borrowing capacity	'	'	'	'	400,000,000	'
Term of loan (in years)	'5 years	'	'	'	'	'
CoStar Group [Member] | Revolving Credit Facility [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Debt instrument borrowing capacity	'	'	'	'	225,000,000	'
Term of loan (in years)	'5 years	'	'	'	'	'
CoStar Group [Member] | Notes Payable to Banks [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Annual amortization, first year after closing (in percent)	'	'	'	'	5.00%	'
Annual amortization, second year after closing (in percent)	'	'	'	'	5.00%	'
Annual amortization, third year after closing (in percent)	'	'	'	'	5.00%	'
Annual amortization, fourth year after closing (in percent)	'	'	'	'	10.00%	'
Annual amortization, fifth year after closing (in percent)	'	'	'	'	15.00%	'
CoStar Group [Member] | Maximum [Member] | Swingline Loan [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Revolving credit sub-facility for swing-line loans and issuances of letters of credit	'	'	'	'	10,000,000	'
CoStar Group [Member] | Maximum [Member] | Letter of Credit [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Revolving credit sub-facility for swing-line loans and issuances of letters of credit	'	'	'	'	$10,000,000	'
Federal Funds Rate [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Basis spread on federal funds rate (in percent)	0.50%	'	'	'	'	'
LIBOR [Member]	'	'	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'	'	'
Basis spread on federal funds rate (in percent)	2.00%	'	'	'	'	'
Debt instrument, basis spread on variable rate, one month interest period (in percent)	'	'	'	'	1.00%	'
Debt instrument, basis spread on variable rate, per annum (in percent)	'	'	'	'	1.00%	'

LONGTERM_DEBT_Details_Covenant

LONG-TERM DEBT (Details - Covenant Calculations)	Apr. 01, 2014
Debt Disclosure [Abstract]	'
Maximum first lien secured leverage ratio for first eight quarters after closing date	400.00%
Maximum first lien secured leverage ratio after eight quarters after closing date (in percent)	350.00%
Maximum total leverage ratio for first eight quarters after closing date (in percent)	500.00%
Maximum total leverage ratio after eight fiscal quarters (in percent)	450.00%

LONGTERM_DEBT_Details_Interest

LONG-TERM DEBT (Details - Interest Expense and Amortization of Debt Issuance Costs) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Apr. 01, 2014	Sep. 30, 2014	Dec. 31, 2013
						Revolving Credit Facility [Member]	Revolving Credit Facility [Member]
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Line of credit facility, amount outstanding	'	'	'	'	$150,000,000	$0	$0
Interest expense, debt	2,698,000	1,736,000	8,066,000	5,249,000	'	'	'
Amortization of debt issuance costs	904,000	760,000	2,459,000	2,273,000	'	'	'
Interest paid	$1,720,000	$1,307,000	$5,436,000	$3,339,000	'	'	'

INCOME_TAXES_Details

INCOME TAXES (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Income Tax Examination [Line Items]	'	'
Tax adjustments from IRS audit	$0	'
Effective income tax rate (in percent)	38.00%	38.00%
LoopNet [Member]	'	'
Income Tax Examination [Line Items]	'	'
Tax adjustments from IRS audit	$0	'

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Details) (USD $)

0 Months Ended

1 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

Nov. 25, 2013

31-May-11

Sep. 30, 2014

Apr. 03, 2014

Apr. 01, 2014

Apr. 03, 2014

Apr. 01, 2014

Apr. 03, 2014

Apr. 01, 2014

Apr. 03, 2014

Apr. 01, 2014

Sep. 30, 2014

Sep. 30, 2014

class_action_lawsuits

current_litigation_matters

Term Loan [Member]

Term Loan [Member]

Term Loan [Member]

Term Loan [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Civix [Member]

LoopNet Stockholders [Member]

CoStar Group [Member]

CoStar Group [Member]

CoStar Group [Member]

CoStar Group [Member]

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt instrument borrowing capacity

'

'

'

'

$400,000,000

'

$400,000,000

'

$225,000,000

'

$225,000,000

'

'

Term of loan (in years)

'

'

'

'5 years

'

'5 years

'

'5 years

'

'5 years

'

'

'

Class action lawsuits brought by alleged LoopNet stockholders (in lawsuits)

'

3

'

'

'

'

'

'

'

'

'

'

'

Loss contingency accrual

'

'

'

'

'

'

'

'

'

'

'

1,500,000

200,000

Loss contingency, value of damages sought

3,700,000

'

'

'

'

'

'

'

'

'

'

'

'

Loss contingency in excess of amount accrued

'

'

'

'

'

'

'

'

'

'

'

$2,200,000

'

Minimum number of current litigation matters

'

'

1

'

'

'

'

'

'

'

'

'

'

SEGMENT_REPORTING_Details

SEGMENT REPORTING (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
			operating_segments
Segment Reporting Information [Line Items]	'	'	'	'	'	'
Number of business segments (in segments)	'	'	2	'	'	'
Summarized information by operating segment [Abstract]	'	'	'	'	'	'
Revenues	$153,056,000	$112,301,000	$419,840,000	$325,333,000	'	'
Property and equipment, net	70,675,000	'	70,675,000	'	57,719,000	'
Goodwill	1,139,917,000	'	1,139,917,000	'	718,587,000	718,078,000
Reconciliation of EBITDA to net income [Abstract]	'	'	'	'	'	'
EBITDA	43,692,000	29,792,000	108,263,000	62,692,000	'	'
Purchase amortization in cost of revenues	-7,790,000	-2,954,000	-18,547,000	-9,007,000	'	'
Purchase amortization in operating expenses	-8,361,000	-3,680,000	-20,696,000	-11,699,000	'	'
Depreciation and other amortization	-4,061,000	-3,388,000	-11,490,000	-9,531,000	'	'
Interest income	46,000	52,000	245,000	239,000	'	'
Interest expense	-2,698,000	-1,736,000	-8,066,000	-5,249,000	'	'
Income tax expense, net	-7,871,000	-7,034,000	-18,763,000	-10,510,000	'	'
Net income	12,957,000	11,052,000	30,946,000	16,935,000	'	'
Reconciliation of operating segment assets to total assets [Abstract]	'	'	'	'	'	'
Total operating segment assets	2,161,473,000	'	2,161,473,000	'	1,354,756,000	'
Investment in subsidiaries	-18,344,000	'	-18,344,000	'	-18,344,000	'
Intersegment receivables	-78,788,000	'	-78,788,000	'	-79,430,000	'
Total assets	2,064,341,000	'	2,064,341,000	'	1,256,982,000	'
Reconciliation of operating segment liabilities to total liabilities [Abstract]	'	'	'	'	'	'
Total operating segment liabilities	645,141,000	'	645,141,000	'	403,892,000	'
Intersegment payables	-73,173,000	'	-73,173,000	'	-74,772,000	'
Total liabilities	571,968,000	'	571,968,000	'	329,120,000	'
North America [Member]	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'
North America corporate allocation	200,000	300,000	900,000	600,000	'	'
Summarized information by operating segment [Abstract]	'	'	'	'	'	'
Revenues	146,899,000	107,230,000	402,074,000	310,762,000	'	'
Property and equipment, net	67,712,000	'	67,712,000	'	53,733,000	'
Goodwill	1,114,363,000	'	1,114,363,000	'	692,639,000	'
Reconciliation of EBITDA to net income [Abstract]	'	'	'	'	'	'
EBITDA	42,929,000	30,855,000	106,387,000	66,609,000	'	'
Reconciliation of operating segment assets to total assets [Abstract]	'	'	'	'	'	'
Total operating segment assets	2,118,504,000	'	2,118,504,000	'	1,311,292,000	'
Reconciliation of operating segment liabilities to total liabilities [Abstract]	'	'	'	'	'	'
Total operating segment liabilities	566,996,000	'	566,996,000	'	324,626,000	'
International [Member]	'	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'	'
International corporate allocation	100,000	100,000	200,000	300,000	'	'
Summarized information by operating segment [Abstract]	'	'	'	'	'	'
Revenues	6,162,000	5,202,000	17,807,000	14,848,000	'	'
Property and equipment, net	2,963,000	'	2,963,000	'	3,986,000	'
Goodwill	25,554,000	'	25,554,000	'	25,948,000	25,439,000
Reconciliation of EBITDA to net income [Abstract]	'	'	'	'	'	'
EBITDA	763,000	-1,063,000	1,876,000	-3,917,000	'	'
Reconciliation of operating segment assets to total assets [Abstract]	'	'	'	'	'	'
Total operating segment assets	42,969,000	'	42,969,000	'	43,464,000	'
Reconciliation of operating segment liabilities to total liabilities [Abstract]	'	'	'	'	'	'
Total operating segment liabilities	78,145,000	'	78,145,000	'	79,266,000	'
External Customers [Member]	'	'	'	'	'	'
Summarized information by operating segment [Abstract]	'	'	'	'	'	'
Revenues	6,157,000	5,071,000	17,766,000	14,571,000	'	'
Intersegment Revenue [Member]	'	'	'	'	'	'
Summarized information by operating segment [Abstract]	'	'	'	'	'	'
Revenues	5,000	131,000	41,000	277,000	'	'
Intersegment Elimination [Member]	'	'	'	'	'	'
Summarized information by operating segment [Abstract]	'	'	'	'	'	'
Revenues	($5,000)	($131,000)	($41,000)	($277,000)	'	'

EQUITY_OFFERING_Details

EQUITY OFFERING (Details) (USD $)	1 Months Ended	9 Months Ended
	Jun. 30, 2014	Sep. 30, 2014	Sep. 30, 2013
Proceeds from (Repurchase of) Equity [Abstract]	'	'	'
Equity offering in period, new shares (in shares)	3,450,000	'	'
New shares Issued, price per share (in dollars per share)	$160	'	'
Proceeds from equity offering, net of transaction costs	$529,360,000	$529,360,000	$0
Payments for underwriting expense	22,100,000	'	'
Payments of equity offering costs	$500,000	'	'