Fair Value Disclosures - Fair Value of Other Financial Instruments Not Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank deposits (included in "Cash and cash equivalents")	$ 267,761	$ 225,853
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank deposits (included in "Cash and cash equivalents")	$ 267,761	225,853
Revolving Credit Facility [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Borrowings under Revolving Credit Facility		75,000
Revolving Credit Facility [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Borrowings under Revolving Credit Facility		75,000
Revolving Credit Facility [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Borrowings under Revolving Credit Facility		$ 75,000