| Selected Balance Sheet Data - Changes in Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | |
|---|---|---|
| Mar. 31, 2014 | Mar. 31, 2013 | |
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Balance at beginning of period | $ (99) | $ (129) | 
| Recoveries (provision) for losses on commissions receivable | 4 | (37) | 
| Write-off of uncollectible commissions receivable | ||
| Balance at end of period | (81) | (129) | 
| Commissions receivable [Member] | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Recoveries (provision) for losses on commissions receivable | $ 18 | |
| X | ||||||||||
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- Details 
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- Definition A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition Amount of direct write-downs of accounts receivable charged against the allowance. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of expense related to write-down of receivables to the amount expected to be collected. Includes, but is not limited to, accounts receivable and notes receivable. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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