Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of assets and liabilities measured at fair value on recurring basis
Interest Rate Derivative Liabilities, at Fair Value Disclosure	$ 322	$ 332
Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Interest Rate Derivative Liabilities, at Fair Value Disclosure	0	0
Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Interest Rate Derivative Liabilities, at Fair Value Disclosure	322	332
Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Interest Rate Derivative Liabilities, at Fair Value Disclosure	0	0
Money market mutual funds [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	16,821	19,957
Money market mutual funds [Member] | Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	16,821	19,957
Money market mutual funds [Member] | Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Money market mutual funds [Member] | Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Government agency bonds [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	7,501	7,509
Government agency bonds [Member] | Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	7,501	7,509
Government agency bonds [Member] | Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Government agency bonds [Member] | Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
United States treasuries [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	4,008	8,041
United States treasuries [Member] | Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	4,008	8,041
United States treasuries [Member] | Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
United States treasuries [Member] | Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Municipal Bonds [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	4,186
Municipal Bonds [Member] | Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	4,186
Municipal Bonds [Member] | Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0
Municipal Bonds [Member] | Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0
Corporate notes [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	6,386	8,453
Corporate notes [Member] | Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	6,386	8,453
Corporate notes [Member] | Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Corporate notes [Member] | Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Certificates of deposit [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	2,523	2,426
Certificates of deposit [Member] | Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	2,523	2,426
Certificates of deposit [Member] | Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Certificates of deposit [Member] | Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Assets, Fair Value Disclosure	0	0
Foreign currency forward contract [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Foreign Currency Contract, Asset, Fair Value Disclosure	94	114
Foreign currency forward contract [Member] | Level 1 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Foreign currency forward contract [Member] | Level 2 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Foreign Currency Contract, Asset, Fair Value Disclosure	94	114
Foreign currency forward contract [Member] | Level 3 [Member]
Schedule of assets and liabilities measured at fair value on recurring basis
Foreign Currency Contract, Asset, Fair Value Disclosure	$ 0	$ 0