Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term marketable securities	$ 0	$ 1,305
Prepaid expenses and other current assets	98,511	102,392
Accrued expenses	(70,654)	(78,967)
Total	(775)	557
Foreign exchange derivative assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Prepaid expenses and other current assets	171	0
Foreign exchange derivative liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued expenses	(166)	0
1.25% Notes Embedded Cash Conversion Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	(49,449)	(57,839)
1.25% Call Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	48,669	57,091
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term marketable securities	0	0
Total	0	0
Level 1 [Member] | Foreign exchange derivative assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Prepaid expenses and other current assets	0	0
Level 1 [Member] | Foreign exchange derivative liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued expenses	0	0
Level 1 [Member] | 1.25% Notes Embedded Cash Conversion Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	0	0
Level 1 [Member] | 1.25% Call Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	0	0
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term marketable securities	0	1,305
Total	5	1,305
Level 2 [Member] | Foreign exchange derivative assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Prepaid expenses and other current assets	171	0
Level 2 [Member] | Foreign exchange derivative liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued expenses	(166)	0
Level 2 [Member] | 1.25% Notes Embedded Cash Conversion Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	0	0
Level 2 [Member] | 1.25% Call Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	0	0
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term marketable securities	0	0
Total	(780)	(748)
Level 3 [Member] | Foreign exchange derivative assets [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Prepaid expenses and other current assets	0	0
Level 3 [Member] | Foreign exchange derivative liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued expenses	0	0
Level 3 [Member] | 1.25% Notes Embedded Cash Conversion Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	(49,449)	(57,839)
Level 3 [Member] | 1.25% Call Option [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	$ 48,669	$ 57,091