Fair Value Measurements (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Interest Rate Swap [Member]
Summary of financial assets measured at fair value on recurring basis
Intangible and other long-term assets		$ 1,904
Non-qualified deferred compensation assets [Member]
Summary of financial assets measured at fair value on recurring basis
Intangible and other long-term assets	11,183	10,597
Non-qualified deferred compensation liabilities [Member]
Summary of financial assets measured at fair value on recurring basis
Accounts payable	2,727	2,790
Other long-term liabilities	12,875	12,975
Contingent Consideration [Member]
Summary of financial assets measured at fair value on recurring basis
Accounts payable	6,251
Level 1 [Member] | Non-qualified deferred compensation assets [Member]
Summary of financial assets measured at fair value on recurring basis
Intangible and other long-term assets	820	815
Level 2 [Member] | Interest Rate Swap [Member]
Summary of financial assets measured at fair value on recurring basis
Intangible and other long-term assets		1,904
Level 2 [Member] | Non-qualified deferred compensation assets [Member]
Summary of financial assets measured at fair value on recurring basis
Intangible and other long-term assets	10,363	9,782
Level 2 [Member] | Non-qualified deferred compensation liabilities [Member]
Summary of financial assets measured at fair value on recurring basis
Accounts payable	2,727	2,790
Other long-term liabilities	12,875	12,975
Level 3 [Member] | Contingent Consideration [Member]
Summary of financial assets measured at fair value on recurring basis
Accounts payable	$ 6,251