Marketable Securities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Marketable Securities [Abstract]
Fair value of investments owned	$ 176.7	$ 45.0
Investments classified as available-for-sale, fair value	$ 92.5	$ 5.5

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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-Publisher SEC

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-Publisher SEC

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