Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Notes Receivable Long-Term [Member]
Balance at beginning of period	$ 375	$ 0
Total gains, realized or unrealized		0
Purchases, (sales), issuances and (settlements), net	(375)	375
Balance at end of period	0	375
Reserve for notes receivable	0
Net balance at December 31, 2016	0
Notes Receivable Current [Member]
Balance at beginning of period	0	150
Total gains, realized or unrealized		0
Purchases, (sales), issuances and (settlements), net	750	(150)
Balance at end of period	750	0
Reserve for notes receivable	(750)
Net balance at December 31, 2016	0
Investments [Member]
Balance at beginning of period	680	3,880
Total gains, realized or unrealized		636
Purchases, (sales), issuances and (settlements), net	0	(3,836)
Balance at end of period	680	$ 680
Reserve for notes receivable	0
Net balance at December 31, 2016	$ 680