Fair Value Measures (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) | Mar. 31, 2015 | Dec. 31, 2014 | Mar. 31, 2014 |
In Thousands, unless otherwise specified |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | $274,888 | | $232,634 | | $411,761 | |
Total liabilities measured at fair value | 123 | | 924 | | 1,050 | |
Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 153,844 | | 145,823 | | 315,862 | |
Total liabilities measured at fair value | 0 | | 0 | | 0 | |
Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 121,044 | | 86,811 | | 95,899 | |
Total liabilities measured at fair value | 123 | | 924 | | 1,050 | |
Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Total liabilities measured at fair value | 0 | | 0 | | 0 | |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | 123 | | 924 | | 1,017 | |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | 0 | | 0 | | 0 | |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | 123 | | 924 | | 1,017 | |
Accrued Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | 0 | | 0 | | 0 | |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | | | | | 33 | |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | | | | | 0 | |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | | | | | 33 | |
Other Long Term Liabilities [Member] | Derivative Financial Instruments, Liabilities [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total liabilities measured at fair value | | | | | 0 | |
Cash Equivalents [Member] | Money Market Funds [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 101,241 | | 94,112 | | 269,786 | |
Cash Equivalents [Member] | Money Market Funds [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 101,241 | | 94,112 | | 269,786 | |
Cash Equivalents [Member] | Money Market Funds [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Cash Equivalents [Member] | Money Market Funds [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Cash Equivalents [Member] | Time Deposits [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 45,221 | | 45,187 | | 39,217 | |
Cash Equivalents [Member] | Time Deposits [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 45,221 | | 45,187 | | 25,129 | |
Cash Equivalents [Member] | Time Deposits [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | | | 14,088 | |
Cash Equivalents [Member] | Time Deposits [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Cash Equivalents [Member] | Certificates of Deposit [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 2,205 | | 1,470 | | | |
Cash Equivalents [Member] | Certificates of Deposit [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | | |
Cash Equivalents [Member] | Certificates of Deposit [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 2,205 | | 1,470 | | | |
Cash Equivalents [Member] | Certificates of Deposit [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | | |
Cash Equivalents [Member] | Repurchase Agreements [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 50,000 | | 40,000 | | 55,000 | |
Cash Equivalents [Member] | Repurchase Agreements [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Cash Equivalents [Member] | Repurchase Agreements [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 50,000 | | 40,000 | | 55,000 | |
Cash Equivalents [Member] | Repurchase Agreements [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Cash Equivalents [Member] | US Government Backed Municipal Bonds [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 480 | | 5,812 | | | |
Cash Equivalents [Member] | US Government Backed Municipal Bonds [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | | |
Cash Equivalents [Member] | US Government Backed Municipal Bonds [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 480 | | 5,812 | | | |
Cash Equivalents [Member] | US Government Backed Municipal Bonds [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | | |
Available-For-Sale Short-Term Investments [Member] | Certificates of Deposit [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 13,453 | [1] | 3,184 | [1] | 9,795 | [1] |
Available-For-Sale Short-Term Investments [Member] | Certificates of Deposit [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | [1] | 0 | [1] | 0 | [1] |
Available-For-Sale Short-Term Investments [Member] | Certificates of Deposit [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 13,453 | [1] | 3,184 | [1] | 9,795 | [1] |
Available-For-Sale Short-Term Investments [Member] | Certificates of Deposit [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | [1] | 0 | [1] | 0 | [1] |
Available-For-Sale Short-Term Investments [Member] | US Government Backed Municipal Bonds [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 39,119 | [1] | 23,598 | [1] | 14,185 | [1] |
Available-For-Sale Short-Term Investments [Member] | US Government Backed Municipal Bonds [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | [1] | 0 | [1] | 0 | [1] |
Available-For-Sale Short-Term Investments [Member] | US Government Backed Municipal Bonds [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 39,119 | [1] | 23,598 | [1] | 14,185 | [1] |
Available-For-Sale Short-Term Investments [Member] | US Government Backed Municipal Bonds [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | [1] | 0 | [1] | 0 | [1] |
Available-For-Sale Short-Term Investments [Member] | US States and Political Subdivisions Debt Securities [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | | | | | 15,028 | [1] |
Available-For-Sale Short-Term Investments [Member] | US States and Political Subdivisions Debt Securities [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | | | | | 15,028 | [1] |
Short-term Investments [Member] | Mutual Fund Shares [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 366 | | 485 | | 529 | |
Short-term Investments [Member] | Mutual Fund Shares [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 366 | | 485 | | 529 | |
Short-term Investments [Member] | Mutual Fund Shares [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Short-term Investments [Member] | Mutual Fund Shares [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 15,787 | | 12,747 | | 2,703 | |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 15,787 | | 12,747 | | 2,703 | |
Other Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Non Current Assets [Member] | Mutual Fund Shares [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 7,016 | | 6,039 | | 5,390 | |
Non Current Assets [Member] | Mutual Fund Shares [Member] | Level 1 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 7,016 | | 6,039 | | 5,390 | |
Non Current Assets [Member] | Mutual Fund Shares [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Non Current Assets [Member] | Mutual Fund Shares [Member] | Level 3 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | 0 | | 0 | | 0 | |
Non Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | | | | | 128 | |
Non Current Assets [Member] | Derivative Financial Instruments, Assets [Member] | Level 2 [Member] | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total assets measured at fair value | | | | | $128 | |
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[1] | (1)B Investments have remaining maturities of less than one year. |