Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value of Financial Instruments
Assets - investment in U.S. Treasury obligations		$ 808
Liabilities - long-term debt (carried at amortized cost)	$ 291,306	296,908
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring
Fair Value of Financial Instruments
Assets - investment in U.S. Treasury obligations		808
Significant other observable inputs (Level 2) | Recurring
Fair Value of Financial Instruments
Liabilities - long-term debt (carried at amortized cost)	291,306	296,908
Carrying Value
Fair Value of Financial Instruments
Assets - investment in U.S. Treasury obligations		808
Liabilities - long-term debt (carried at amortized cost)	286,046	287,179
Fair Value
Fair Value of Financial Instruments
Assets - investment in U.S. Treasury obligations		808
Liabilities - long-term debt (carried at amortized cost)	$ 291,306	$ 296,908