Fair Value Measurements - Schedule Of Assets And Liabilities Measured At Fair Value On Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total	$ 31,677		$ 34,798
Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	1,659		1,779
Pre-Refunded Bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	14,816		14,877
Short-Term Bond Mutual Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	14,178		17,196
Foreign Exchange Forward Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	136		121
Liabilities measured at fair value on a recurring basis	(102)		(131)
Deferred Compensation Plan Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	888	[1]	825	[1]
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total	15,066		18,021
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Pre-Refunded Bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Short-Term Bond Mutual Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	14,178		17,196
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Foreign Exchange Forward Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Liabilities measured at fair value on a recurring basis	0
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Deferred Compensation Plan Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	888		825	[1]
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total	16,611		16,777
Significant Other Observable Inputs (Level 2) [Member] | Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	1,659		1,779
Significant Other Observable Inputs (Level 2) [Member] | Pre-Refunded Bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	14,816		14,877
Significant Other Observable Inputs (Level 2) [Member] | Short-Term Bond Mutual Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Significant Other Observable Inputs (Level 2) [Member] | Foreign Exchange Forward Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	136		121
Liabilities measured at fair value on a recurring basis	(102)		(131)
Significant Other Observable Inputs (Level 2) [Member] | Deferred Compensation Plan Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0	[1]	0	[1]
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total	0		0
Significant Unobservable Inputs (Level 3) [Member] | Certificates of Deposit [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Significant Unobservable Inputs (Level 3) [Member] | Pre-Refunded Bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Significant Unobservable Inputs (Level 3) [Member] | Short-Term Bond Mutual Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Significant Unobservable Inputs (Level 3) [Member] | Foreign Exchange Forward Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	0		0
Liabilities measured at fair value on a recurring basis	0
Significant Unobservable Inputs (Level 3) [Member] | Deferred Compensation Plan Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value on a recurring basis	$ 0	[1]	$ 0	[1]

[1] Recorded as an Other asset with an offsetting liability for the obligation to its employees in Other liabilities.