Summary of Significant Accounting Policies Allowance for Doubtful Accounting Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 17	$ 5	$ 25
Additions / deductions charged to earnings	(5)	14	(20)
Uncollectible receivables written off, net of recoveries	0	(2)	0
Balance at end of year	$ 12	$ 17	$ 5