Summary of Cash and Cash Equivalents and Investments by Balance Sheet Classification (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Cash And Cash Equivalents And Investments
Cash and cash equivalents	$ 197,356		$ 192,165
Short-term investments	41,339		36,688
Long-term investments	10,790		24,964
Total cash and cash equivalents and investments	249,485		253,817
Cash and cash equivalents	197,356	[1]	192,165	[1]
Cash and cash equivalents and investments	249,612	[1]	253,771	[1]
Short-term Investments
Cash And Cash Equivalents And Investments
Cash and cash equivalents and investments	41,360	[1]	36,774	[1]
Long Term Investments
Cash And Cash Equivalents And Investments
Cash and cash equivalents and investments	$ 10,896	[1]	$ 24,832	[1]

[1] See Note 16 - Fair Value Measurements for details regarding fair value measurements.