Components of Debt Obligations (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Notes payable to former shareholders of acquired businesses	$ 11,000us-gaap_OtherNotesPayable	$ 17,000us-gaap_OtherNotesPayable
Other		14us-gaap_OtherLongTermDebt
Total debt	711,000us-gaap_LongTermDebt	717,014us-gaap_LongTermDebt
Less current portion	11,000us-gaap_LongTermDebtCurrent	6,014us-gaap_LongTermDebtCurrent
Long-term debt, net of current portion	700,000us-gaap_LongTermDebtNoncurrent	711,000us-gaap_LongTermDebtNoncurrent
Total debt	711,000us-gaap_LongTermDebt	717,014us-gaap_LongTermDebt
6 3/4 % Senior Notes Due 2020
Debt Instrument [Line Items]
Senior notes	400,000	400,000
6.0% Senior Notes Due 2022
Debt Instrument [Line Items]
Senior notes	$ 300,000	$ 300,000

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Including the current and noncurrent portions, the carrying value of notes payable which were initially due after one year or beyond the normal operating cycle, if longer, and which are not otherwise defined in the taxonomy.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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