Fair Value Measurements (Fair Value Measurements at Reporting Date Using) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Assets, fair value disclosure	$ 553	$ 1,359
Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	553	1,359
Fuel Hedge Contracts [Member]
Assets, fair value disclosure		449
Liabilities, fair value disclosure	1,695
Fuel Hedge Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure		449
Liabilities, fair value disclosure	1,695
Foreign Exchange Contract [Member]
Assets, fair value disclosure	137	155
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	137	155
Interest Rate Contract [Member]
Assets, fair value disclosure	416	755
Interest Rate Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, fair value disclosure	$ 416	$ 755