Future Minimum Capital Lease Payments and Present Value of Minimum Lease Payments for All Capital Leases (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Schedule of Capital Lease Obligations [Line Items]
2012	$ 5,563
2013	7,985
2014	8,211
2015	8,357
2016	7,601
Thereafter	34,464
Remaining capital lease payments	72,181
Less: amounts representing imputed interest	(24,017)
Present value of minimum lease payments	48,164
Less: current portion	(3,271)	(2,154)
Capital lease obligations	$ 44,893	$ 38,923

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid within one year (or one operating cycle, if longer) of the balance sheet date.

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The total of contractually required rental payments on leases meeting the criteria for capitalization.

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Contractually required rental payments on leases meeting the criteria for capitalization, due within one year of the balance sheet date.

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Contractually required rental payments on leases meeting the criteria for capitalization, due within the fifth year from the balance sheet date.

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Contractually required rental payments on leases meeting the criteria for capitalization, due within the fourth year from the balance sheet date.

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Contractually required rental payments on leases meeting the criteria for capitalization, due within the third year from the balance sheet date.

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Contractually required rental payments on leases meeting the criteria for capitalization, due within the second year from the balance sheet date.

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Contractually required rental payments due on leases meeting the criteria for capitalization, after the fifth year from the balance sheet date.

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Amount necessary to reduce net minimum lease payments to present value calculated at the lesser of the interest rate implicit in the lease (if known) or the entity's incremental borrowing rate (as defined) at inception of the lease.

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The discounted value of future cash flows under leases meeting the criteria for capitalization.

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