Investments and Fair Value Measurements (Fair Value of Assets) (Details) (USD $) In Thousands, unless otherwise specified
|
Jun. 30, 2012
|
Dec. 31, 2011
|
Government Obligations [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
$ 81,799 |
$ 138,769 |
Corporate Bonds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
78,163 |
61,323 |
Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
17,136 |
29,959 |
Equity Securities and Exchange-traded Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
29,486 |
8,271 |
Mutual Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
10,894 |
9,595 |
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Trading securities, fair value |
5,184 |
5,491 |
Cash equivalents, fair value |
9,485 |
30,818 |
Total investments, fair value |
232,147 |
284,226 |
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Government Obligations [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
81,799 |
138,769 |
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Corporate Bonds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
78,163 |
61,323 |
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
17,136 |
29,959 |
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Equity Securities and Exchange-traded Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
29,486 |
8,271 |
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Mutual Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
10,894 |
9,595 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Trading securities, fair value |
5,184 |
5,491 |
Cash equivalents, fair value |
9,485 |
30,818 |
Total investments, fair value |
55,049 |
54,175 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Government Obligations [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Bonds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities and Exchange-traded Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
29,486 |
8,271 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mutual Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
10,894 |
9,595 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Trading securities, fair value |
0 |
0 |
Cash equivalents, fair value |
0 |
0 |
Total investments, fair value |
177,098 |
230,051 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Government Obligations [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
81,799 |
138,769 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
78,163 |
61,323 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
17,136 |
29,959 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities and Exchange-traded Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mutual Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Trading securities, fair value |
0 |
0 |
Cash equivalents, fair value |
0 |
0 |
Total investments, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Government Obligations [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Bonds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities and Exchange-traded Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
0 |
0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mutual Funds [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Available-for-sale securities, fair value |
$ 0 |
$ 0 |