Components of Interest Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument, Redemption [Line Items]
Interest on borrowings and related fees	$ 91,866us-gaap_InterestExpenseBorrowings	$ 80,263us-gaap_InterestExpenseBorrowings	$ 56,080us-gaap_InterestExpenseBorrowings
Accretion of original issue discount	0	431	1,367
Amortization of debt issuance costs	4,197us-gaap_AmortizationOfFinancingCosts	3,413us-gaap_AmortizationOfFinancingCosts	2,695us-gaap_AmortizationOfFinancingCosts
Capitalized interest	(7,232)us-gaap_InterestPaidCapitalized	(5,266)us-gaap_InterestPaidCapitalized	(803)us-gaap_InterestPaidCapitalized
Interest expense	$ 88,831us-gaap_InterestExpense	$ 78,841us-gaap_InterestExpense	$ 59,339us-gaap_InterestExpense
Convertible Debt
Debt Instrument, Redemption [Line Items]
Annual interest rate			4.50%

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Aggregate amount of interest expense on all borrowings.

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The amount of cash paid during the current period for interest that is capitalized.

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