Interest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Debt Instrument [Line Items]
Total interest expense	$ 10,184	$ 11,694
Convertible Senior Notes and Senior Secured Credit Facility [Member]
Debt Instrument [Line Items]
Interest expense	6,229	7,938
Amortization of discounts and debt issuance costs	3,955	3,756
Total interest expense	$ 10,184	$ 11,694

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

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

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

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