Fair Values of Financial Instruments (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Assets:
Cash and cash equivalents	$ 36,715	$ 18,568
Investments	3,723	26,213
Total assets at fair value	40,438	44,781
Level 1 [Member]
Assets:
Cash and cash equivalents	36,715	18,568
Investments	2,800
Total assets at fair value	39,515	18,568
Level 2 [Member]
Assets:
Cash and cash equivalents
Investments		25,311
Total assets at fair value		25,311
Level 3 [Member]
Assets:
Investments	923	902
Total assets at fair value	$ 923	$ 902