Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Equity securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	$ 56	$ 44
U.S. Treasury securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	6,089	6,239
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	56	44
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	6,089	6,239
Significant Other Observable Inputs (Level 2) [Member] | Equity securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	0	0
Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	0	0
Significant Unobservable Inputs (Level 3) [Member] | Equity securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	0	0
Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	$ 0	$ 0