Subsequent Events - Additional Information (Detail) (USD $)	9 Months Ended		1 Months Ended	9 Months Ended
Sep. 30, 2014	Dec. 31, 2013	Oct. 31, 2014 Credit Agreement [Member]	Sep. 30, 2014 Credit Agreement [Member]	Oct. 31, 2014 Credit Agreement [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Credit agreement, borrowing capacity		$ 70,000,000	$ 70,000,000		$ 120,000,000
Outstanding borrowings under the revolving credit facility	0		0
Credit agreement, maturity date	Jun. 30, 2016			Jun. 30, 2016
Minimum cash, cash equivalents and investments under covenant term				$ 200,000,000	$ 190,000,000
Credit facility agreement amended compliance			The terms of the amended Credit Agreement remain largely unchanged with the exception of maintaining a minimum three month average cash, cash equivalents and investments balance of $190 million, subject to certain adjustments for real estate buyout transactions.

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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