Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Equity Securities [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	$ 2,770	$ 56
U.S. Treasury Securities (Cash Equivalents) [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	1,002	4,089
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	2,770	56
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury Securities (Cash Equivalents) [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	1,002	4,089
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 (Cash Equivalents) [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 (Cash Equivalents) [Member]
Assets measured at fair value on recurring basis [Abstract]
Fair value assets	$ 0	$ 0