Investments - Summary of Investments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments Schedule [Abstract]
Marketable securities	$ 50,251us-gaap_MarketableSecurities	$ 28,968us-gaap_MarketableSecurities
Equity method investments	7,209us-gaap_EquityMethodInvestments	4,070us-gaap_EquityMethodInvestments
Nonqualified retirement plan assets	5,063	4,220
Other investments	925us-gaap_OtherInvestments
Total investments	$ 63,448us-gaap_Investments	$ 37,258us-gaap_Investments

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

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- Definition

Sum of the carrying amounts as of the balance sheet date of all investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

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- Definition

Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Paragraph 1

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- Definition

Other investments not otherwise specified in the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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- Definition

Investments In Nonqualified Retirement Plan Assets

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No definition available.

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