Investments in debt and equity securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Investment Holdings [Line Items]
Debt securities	$ 20,430	$ 82,879
Investments in equity securities	36,603	39,143
Equity Securities, FV-NI	36,603	39,143
Total	57,033	122,022
Debt securities, short-term investments	5,419	67,872
Short-term investments	11,713	77,693
Debt securities, long-term investments	15,011	15,007
Long-term investments	45,320	44,329
Certificates of deposit and other time deposits
Investment Holdings [Line Items]
Debt securities	20,430	82,879
Investments in equity securities	0	0
Total	20,430	82,879
Investments in mutual funds and common stocks
Investment Holdings [Line Items]
Debt securities	0	0
Investments in equity securities	36,603	39,143
Total	36,603	39,143
Short-term Investments
Investment Holdings [Line Items]
Investments in equity securities	6,294	9,821
Long-term Investments
Investment Holdings [Line Items]
Equity Securities, FV-NI, Noncurrent	$ 30,309	$ 29,322