Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014 Company	Dec. 31, 2013 Company
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of private companies equity security held	2	2
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 230,955	$ 236,432
Carrying Value [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value	453	453
Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 235,000	$ 226,789