Fair Value Measurements - Fair Value of Other Financial Instruments Not Measured on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Bank deposits (included in "Cash and cash equivalents")	$ 228,788	$ 71,301	$ 70,136	$ 107,717
Convertible Notes	208,414	196,007
Fair value, measurements, nonrecurring [Member] | Fair value [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Bank deposits (included in "Cash and cash equivalents")	39,696	22,608
Convertible Notes	277,145	234,813
Fair value, measurements, nonrecurring [Member] | Level 1 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Bank deposits (included in "Cash and cash equivalents")	39,696	22,608
Convertible Notes
Fair value, measurements, nonrecurring [Member] | Level 2 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Bank deposits (included in "Cash and cash equivalents")
Convertible Notes	277,145	234,813
Fair value, measurements, nonrecurring [Member] | Level 3 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Bank deposits (included in "Cash and cash equivalents")
Convertible Notes