Financial Instruments Measured at Fair Value (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, available-for-sale securities	$ 67,903	$ 60,820
Interest rate swaps	(10,832)	(3,009)
Foreign exchange contracts	107	649
Contingent consideration	(806)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	56,158	57,162
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, available-for-sale securities	67,903	60,820
Interest rate swaps	0	0
Foreign exchange contracts	0	0
Contingent consideration	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	67,903	60,820
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, available-for-sale securities	0	0
Interest rate swaps	(10,832)	(3,009)
Foreign exchange contracts	107	649
Contingent consideration	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	(10,939)	(3,658)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, available-for-sale securities	0	0
Interest rate swaps	0	0
Foreign exchange contracts	0	0
Contingent consideration	(806)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	$ (806)	$ 0