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Summary of Significant Accounting Policies - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2016 USD ($) Customer | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Summary Of Significant Accounting Policy [Line Items] |  |  |
Original maturities | 90 days |  |
Number of customers accounted for revenues or accounts receivable greater than 2% of total | Customer | 0 |  |
Annual goodwill impairment test, period | November 30th |  |
Goodwill impairment charges | $ 0 | $ 0 | $ 0
Non-current deferred rent liabilities | 7,400,000 | 6,400,000 |
Foreign exchange gains (losses) | $ 100,000 |  | $ (100,000)
Percentage of expense over the service period on share based awards | 100.00% |  |
Unamortized fair value stock based compensation | $ 15,500,000 |  |
Weighted average remaining recognition period | 2 years 6 months |  |
ASU No. 2016-09 [Member] |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |
Change in reclassification of tax withholding | $ 2,100,000 | $ 1,500,000 |
Research Service Revenue [Member] | Customer Concentration Risk [Member] |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |
Customer accounted for percentage | 2.00% |  |
Accounts Receivable [Member] | Credit Concentration Risk [Member] |  |  |
Summary Of Significant Accounting Policy [Line Items] |  |  |
Customer accounted for percentage | 2.00% |  |

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- Definition An element designated to encapsulate any additional information related to cash and cash equivalents not otherwise addressed by the existing taxonomy. Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 + Details
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