Schedule of Investments in Mutual Funds (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]
Cost	$ 180,143	$ 144,353	$ 59,598
Unrealized gain, net	6,699	5,475	948
Fair value	186,842	149,828	60,546
Gross realized gains	14,619	3,600	3,012
Proceeds on sales of mutual funds	305,298	200,836	238,604
Purchases of mutual funds	$ 349,791	$ 294,010	$ 270,685

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Amount of unrealized gain (loss) on investments in debt and equity securities classified as available-for-sale securities.

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The cash outflow for securities or other assets acquired, which qualify for treatment as an investing activity and are to be liquidated, if necessary, within the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the short-term.

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The cash inflow from sales of all investments, including securities and other assets, having ready marketability and intended by management to be liquidated, if necessary, within the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the short-term.

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