Summary of Cash, Cash Equivalents and Marketable Securities (Detail) (USD $)
In Thousands, unless otherwise specified |
Jun. 30, 2013
|
Dec. 31, 2012
|
Jun. 30, 2012
|
Dec. 31, 2011
|
---|---|---|---|---|
Cash, cash equivalents and marketable securities [Line Items] | ||||
Amortized Cost | $ 504,307 | $ 387,196 | ||
Estimated Fair Value | 504,307 | 387,196 | ||
Cash and cash equivalents | 504,307 | 387,196 | 154,543 | 82,076 |
Cash [Member]
|
||||
Cash, cash equivalents and marketable securities [Line Items] | ||||
Amortized Cost | 350,469 | 343,548 | ||
Estimated Fair Value | 350,469 | 343,548 | ||
Cash and cash equivalents | 350,469 | 343,548 | ||
Money market funds [Member]
|
||||
Cash, cash equivalents and marketable securities [Line Items] | ||||
Amortized Cost | 2,768 | 43,648 | ||
Estimated Fair Value | 2,768 | 43,648 | ||
Cash and cash equivalents | 2,768 | 43,648 | ||
Time deposits [Member]
|
||||
Cash, cash equivalents and marketable securities [Line Items] | ||||
Amortized Cost | 151,070 | |||
Estimated Fair Value | 151,070 | |||
Cash and cash equivalents | $ 151,070 |