Income Taxes - Summary of Tax Effects of Temporary Differences (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Intangible assets	$ 36,340	$ 43,827
Net operating losses	21,547	23,705
Compensation accruals	6,757	6,280
Investments	8,717us-gaap_DeferredTaxAssetsInvestments	5,111us-gaap_DeferredTaxAssetsInvestments
Unrealized loss/(gain)	2,362	(2,357)
Other	46us-gaap_DeferredTaxAssetsOther	1,581us-gaap_DeferredTaxAssetsOther
Gross deferred tax assets	75,769us-gaap_DeferredTaxAssetsGross	78,147us-gaap_DeferredTaxAssetsGross
Valuation allowance	(2,397)	(35)	(1,600)
Gross deferred tax assets after valuation allowance	73,372us-gaap_DeferredTaxAssetsNet	78,112us-gaap_DeferredTaxAssetsNet
Deferred tax liabilities:
Intangible assets	(12,718)	(13,078)
Other investments	(492)	(534)
Gross deferred tax liabilities	(13,210)us-gaap_DeferredIncomeTaxLiabilities	(13,612)us-gaap_DeferredIncomeTaxLiabilities
Deferred tax assets, net	$ 60,162us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 64,500us-gaap_DeferredTaxAssetsLiabilitiesNet

Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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