Fair Value Measurements (Financial Assets Measured at Fair Value on a Recurring Basis) (Detail) (USD $) | Mar. 31, 2015 | Dec. 31, 2014 |
In Thousands, unless otherwise specified |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | $141,191 | $167,382 |
Amortized Cost | 137,753 | 165,121 |
Cash and Cash Equivalents | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 102,994 | 103,253 |
Amortized Cost | 102,994 | 103,255 |
Cash and Cash Equivalents | Cash | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 26,642 | 30,105 |
Amortized Cost | 26,642 | 30,105 |
Cash and Cash Equivalents | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 9,370 | 11,629 |
Amortized Cost | 9,370 | 11,630 |
Cash and Cash Equivalents | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 66,982 | 61,519 |
Amortized Cost | 66,982 | 61,520 |
Short-term Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 31,394 | 58,453 |
Amortized Cost | 31,383 | 58,438 |
Short-term Investments | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 24,394 | 51,453 |
Amortized Cost | 24,383 | 51,438 |
Short-term Investments | U.S. government agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 7,000 | 7,000 |
Amortized Cost | 7,000 | 7,000 |
Restricted cash equivalents and investments | Restricted cash equivalents and investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 3,000 | 3,000 |
Amortized Cost | 3,000 | 3,000 |
Equity Investment in Publicly Traded Securities | Publicly Traded Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 2,648 | 2,676 |
Amortized Cost | 376 | 428 |
Related Party Transaction [Domain] | Warrants issued by Rhapsody | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 1,155 | |
Amortized Cost | 0 | |
Level 1 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 45,660 | 51,410 |
Level 1 | Cash and Cash Equivalents | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 36,012 | 41,734 |
Level 1 | Cash and Cash Equivalents | Cash | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 26,642 | 30,105 |
Level 1 | Cash and Cash Equivalents | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 9,370 | 11,629 |
Level 1 | Cash and Cash Equivalents | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 1 | Short-term Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 7,000 | 7,000 |
Level 1 | Short-term Investments | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 1 | Short-term Investments | U.S. government agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 7,000 | 7,000 |
Level 1 | Restricted cash equivalents and investments | Restricted cash equivalents and investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 1 | Equity Investment in Publicly Traded Securities | Publicly Traded Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 2,648 | 2,676 |
Level 1 | Related Party Transaction [Domain] | Warrants issued by Rhapsody | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | |
Level 2 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 94,376 | 115,972 |
Level 2 | Cash and Cash Equivalents | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 66,982 | 61,519 |
Level 2 | Cash and Cash Equivalents | Cash | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 2 | Cash and Cash Equivalents | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 2 | Cash and Cash Equivalents | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 66,982 | 61,519 |
Level 2 | Short-term Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 24,394 | 51,453 |
Level 2 | Short-term Investments | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 24,394 | 51,453 |
Level 2 | Short-term Investments | U.S. government agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 2 | Restricted cash equivalents and investments | Restricted cash equivalents and investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 3,000 | 3,000 |
Level 2 | Equity Investment in Publicly Traded Securities | Publicly Traded Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 2 | Related Party Transaction [Domain] | Warrants issued by Rhapsody | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | |
Level 3 | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 1,155 | 0 |
Level 3 | Cash and Cash Equivalents | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Cash and Cash Equivalents | Cash | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Cash and Cash Equivalents | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Cash and Cash Equivalents | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Short-term Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Short-term Investments | Corporate notes and bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Short-term Investments | U.S. government agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Restricted cash equivalents and investments | Restricted cash equivalents and investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Equity Investment in Publicly Traded Securities | Publicly Traded Investments | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | 0 | 0 |
Level 3 | Related Party Transaction [Domain] | Warrants issued by Rhapsody | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] | | |
Financial assets fair value | $1,155 | |