Financial Instruments FInancial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 24,115	$ 24,199
Deferred Compensation Liability, Current and Noncurrent	29,481	29,153
Financial and Nonfinancial Liabilities, Fair Value Disclosure	30,480	30,235
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Deferred Compensation Liability, Current and Noncurrent	0	0
Financial and Nonfinancial 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	24,115	24,199
Deferred Compensation Liability, Current and Noncurrent	29,481	29,153
Financial and Nonfinancial Liabilities, Fair Value Disclosure	30,480	30,235
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
Deferred Compensation Liability, Current and Noncurrent	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0
Interest Rate Swap No. 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	335	201
Interest Rate Swap No. 2 [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	0	0
Interest Rate Swap No. 2 [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	335	201
Interest Rate Swap No. 2 [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	0	0
Interest Rate Swap No. 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	664	881
Interest Rate Swap No. 1 [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	0	0
Interest Rate Swap No. 1 [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	664	881
Interest Rate Swap No. 1 [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	$ 0	$ 0