Fair Value Measures Fair Value Measures (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) (USD $) | Dec. 31, 2013 | Dec. 31, 2012 |
In Thousands, unless otherwise specified |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | $367,420 | $184,139 |
Liabilities, Fair Value Disclosure | 1,247 | 1,322 |
Fair Value, Inputs, Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 220,930 | 99,972 |
Liabilities, Fair Value Disclosure | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 146,490 | 84,167 |
Liabilities, Fair Value Disclosure | 1,247 | 1,322 |
Fair Value, Inputs, Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Liabilities, Fair Value Disclosure | 0 | 0 |
Money Market Funds [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 175,624 | 70,857 |
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 175,624 | 70,857 |
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Bank Time Deposits [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 34,637 | 25,035 |
Bank Time Deposits [Member] | Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 25,111 | 25,035 |
Bank Time Deposits [Member] | Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 9,526 | 0 |
Bank Time Deposits [Member] | Fair Value, Inputs, Level 3 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Certificates of Deposit [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 735 | 2,450 |
Certificates of Deposit [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 9,546 | 7,596 |
Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 735 | 2,450 |
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 9,546 | 7,596 |
Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Repurchase Agreements [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 45,000 | 25,000 |
Repurchase Agreements [Member] | Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Repurchase Agreements [Member] | Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 45,000 | 25,000 |
Repurchase Agreements [Member] | Fair Value, Inputs, Level 3 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
U.S. Government-Backed Municipal Bonds [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 9,898 | 5,348 |
U.S. Government-Backed Municipal Bonds [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 14,764 | 14,425 |
U.S. Government-Backed Municipal Bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
U.S. Government-Backed Municipal Bonds [Member] | Fair Value, Inputs, Level 1 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
U.S. Government-Backed Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 9,898 | 5,348 |
U.S. Government-Backed Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 14,764 | 14,425 |
U.S. Government-Backed Municipal Bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Cash Equivalents [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
U.S. Government-Backed Municipal Bonds [Member] | Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Short-term municipal bond fund [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 15,004 | ' |
Short-term municipal bond fund [Member] | Fair Value, Inputs, Level 1 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 15,004 | ' |
Short-term municipal bond fund [Member] | Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | ' |
Short-term municipal bond fund [Member] | Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | ' |
Variable Rate Demand Obligation [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 52,105 | 22,640 |
Variable Rate Demand Obligation [Member] | Fair Value, Inputs, Level 1 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Variable Rate Demand Obligation [Member] | Fair Value, Inputs, Level 2 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 52,105 | 22,640 |
Variable Rate Demand Obligation [Member] | Fair Value, Inputs, Level 3 [Member] | Available-for-sale Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Derivative Financial Instruments, Assets [Member] | Other Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 4,892 | 6,219 |
Derivative Financial Instruments, Assets [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 24 | 489 |
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 1 [Member] | Other Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 1 [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 2 [Member] | Other Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 4,892 | 6,219 |
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 2 [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 24 | 489 |
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Other Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Mutual Fund Shares [Member] | Trading Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 336 | ' |
Mutual Fund Shares [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 4,855 | 4,080 |
Mutual Fund Shares [Member] | Fair Value, Inputs, Level 1 [Member] | Trading Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 336 | ' |
Mutual Fund Shares [Member] | Fair Value, Inputs, Level 1 [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 4,855 | 4,080 |
Mutual Fund Shares [Member] | Fair Value, Inputs, Level 2 [Member] | Trading Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | ' |
Mutual Fund Shares [Member] | Fair Value, Inputs, Level 2 [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Mutual Fund Shares [Member] | Fair Value, Inputs, Level 3 [Member] | Trading Securities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | ' |
Mutual Fund Shares [Member] | Fair Value, Inputs, Level 3 [Member] | Non Current Assets [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, Fair Value Disclosure | 0 | 0 |
Derivative Financial Instruments, Liabilities [Member] | Accrued Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | 1,152 | 1,322 |
Derivative Financial Instruments, Liabilities [Member] | Other Long Term Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | 95 | ' |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 1 [Member] | Accrued Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | 0 | 0 |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 1 [Member] | Other Long Term Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | 0 | ' |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 2 [Member] | Accrued Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | 1,152 | 1,322 |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 2 [Member] | Other Long Term Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | 95 | ' |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Accrued Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | 0 | 0 |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Other Long Term Liabilities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Liabilities, Fair Value Disclosure | $0 | ' |