Cash Equivalents and Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified			9 Months Ended
Sep. 30, 2013 Money Market Funds [Member]	Dec. 31, 2012 Money Market Funds [Member]	Sep. 30, 2013 Minimum [Member]	Sep. 30, 2013 Maximum [Member]
Schedule of Investments [Line Items]
Money market funds at fair value	$ 2.4	$ 11.1
Short-Term investments maturity period, in years				1 year
Long-Term investments maturity period, in years			1 year	7 years

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant