Fair Value Measurements (Financial assets and liabilities measured at fair value on a recurring basis) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Non-Qualified Deferred Compensation Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets	$ 11,858	$ 12,982
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets	4,860	4,183
Non Qualified Deferred Compensation Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable	661	2,291
Other long-term liabilities	17,440	14,720
Level 1 [Member] | Non-Qualified Deferred Compensation Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets	$ 368	$ 1,481
Level 1 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets
Level 1 [Member] | Non Qualified Deferred Compensation Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable
Other long-term liabilities
Level 2 [Member] | Non-Qualified Deferred Compensation Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets	$ 11,490	$ 11,501
Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets	4,860	4,183
Level 2 [Member] | Non Qualified Deferred Compensation Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable	661	2,291
Other long-term liabilities	$ 17,440	$ 14,720
Level 3 [Member] | Non-Qualified Deferred Compensation Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets
Level 3 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible and other long-term assets
Level 3 [Member] | Non Qualified Deferred Compensation Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable
Other long-term liabilities